Ventilation system

ABSTRACT

The present invention relates to an apparatus for ventilation systems which include an element for the transfer of heat from warm exhaust air (taken from inside a building) to cooler exterior fresh air which is drawn into the building. The present invention in particular provides an apparatus whereby, during a defrost cycle, interior air may circulate through both of the fresh air and exhaust air paths for delivery back into the building, i.e. the warm interior air, used as defrost air, may be able to circulate from the interior of the building into the ventilation apparatus and back to the interior of the building. The apparatus can thus use interior air as defrost air while diminishing or avoiding the creation of a negative air pressure in the building.

BACKGROUND OF THE INVENTION

[0001] The present invention generally relates to an apparatus forventilation systems which have means for the transfer of sensible heatand/or water moisture between exhaust air (taken from inside a building)and exterior fresh air (drawn into the building). Such an apparatus may,for example, have means for the transfer of sensible heat and/or watermoisture from warm exhaust air to cooler exterior fresh air, the systemsusing warm interior air as defrost air for defrosting the systems duringcool weather.

[0002] The present invention, in one particular aspect, relates to anapparatus for ventilation systems which have at least one rotary heatexchanger wheel for the transfer of heat (and/or water moisture) fromwarm exhaust air (taken from inside a building) to cooler exterior freshair (drawn into the building).

[0003] The present invention, in another particular aspect, relates to aventilation apparatus for ventilation systems having an exchanger bodywhich may comprise one or more heat exchanger elements of the same ordifferent type e.g. one or more rotary and/or one or more stationary(i.e. non-rotary) exchanger elements or cores.

[0004] The present invention, in a further particular aspect, relates toa ventilation apparatus provided with means for balancing fresh air andexhaust air flow through the operating ventilation apparatus; a methodfor balancing airflow though the apparatus is also provided.

[0005] Sensible heat and/or water moisture recovery ventilation systemsare known which function to draw fresh exterior air into a building andto exhaust stale interior air to the outside. The systems are providedwith appropriate ducting, channels and the like which define a fresh airpath and an exhaust air path whereby interior air of a building may beexchanged with exterior ambient air; during ventilation the air in onepath is not normally allowed to mix with the air in the other path.

[0006] A sensible heat and/or water moisture recovery ventilator deviceor apparatus, which may form part of a ventilation system, in additionto being provided with corresponding air paths may also be provided withone or more exchanger elements or cores, e.g. one or more rotary and/orstationary (i.e. non-rotary) exchanger elements or cores. Heat recoveryventilation devices may also have a housing or cabinet; such enclosuresmay for example be of sheet metal construction (e.g. the top, bottom,side walls and any door, etc. may be made from panels of sheet metal).The heat exchanging core(s), as well as other elements of the devicesuch as, for example, channels or ducts which define air paths,filtration means, insolation and if desired one or more fans for movingair through the fresh air and exhaust air paths may be disposed in theenclosure. Such ventilation devices may be disposed on the outside of orwithin a building such as a house, commercial building or the like;appropriate insulation may be provided around any duct work needed toconnect the device to the fresh air source and the interior air of thebuilding. A stationary heat exchanger element(s) may, for example, takethe form of the (air-to-air) heat exchanger element as shown in U.S.Pat. No. 5,002,118 the contents of which are incorporated herein byreference. Thus, the heat exchanger element(s) may have the form of arectangular parallepiped and may define a pair of air paths which aredisposed at right angles to each other; these exchanger element(s) maybe disposed such that the air paths are diagonally oriented so that theyare self draining (i.e. with respect to any condensed or unfrozenwater).

[0007] Another known type of exchanger element is the rotary thermaland/or desiccant wheel; such (air-to-air) exchanger wheels may have anair permeable heat exchange matrix which provides passagewaystherethrough through which an air stream may flow. The exchanger matrixmay, for example, comprise a plurality of parallel flow channels (seefor example U.S. Pat. No. 4,769,053) or even a random matrix media (seefor example U.S. Pat. No. 5,238,052). Such exchangers may be configuredand disposed such that as they rotate they may transfer a member of thegroup comprising i) sensible heat and ii) sensible heat and latent heat,between two or more streams of air through which the exchangersrotationally pass through. Such rotary heat exchangers may be disposedin a housing which is suitably baffled such that a rotating exchangerwheel may pass through the fresh air and exhaust air streams withminimal intermixing thereof (i.e. for air-to-air transfer oflatent/sensible heat).

[0008] Thus, for example, as a suitably configured rotary transfer coreslowly rotates between outgoing and ingoing air the higher temperatureairstream can give up sensible energy to the core which energy maythereafter be given up by the core to the lower temperature air stream;please see, for example, U.S. Pat. No. 3,844,737. Alternatively, asuitably configured rotary core may capture and release latent energy inthe form of water moisture i.e. the core may transfer water vapour ormoisture from one air stream to another air stream; please see, forexample, U.S. Pat. Nos. 3,800,515, 3,844,737, 4,225,171, and 4,875,520.A rotary energy transfer core or wheel may of course transfer bothsensible and latent heat between fresh air and exhaust air; please see,for example, Canadian patent no. 1,285,931, and U.S. Pat. Nos.4,769,053, 4,172,164,4,093,435, and 5,238,052. The entire contents ofthe above mentioned patents are herein incorporated by reference.

[0009] During the winter season, the outside air is not only cool but itis also relatively dry. Accordingly, if cool dry outside air is broughtinto a building and the warm moist interior air of the building ismerely exhausted to the outside, the air in the building may as aconsequence become uncomfortably dry. A relatively comfortable level ofhumidity may be maintained in a building by inter alia exploiting anabove mentioned desiccant type thermal wheel for transferring water fromthe stale outgoing air to the relatively dry fresh incoming air. Duringwinter these types of heat exchangers may transfer up to 80% of themoisture contained in the exhaust air to the fresh supply air.Advantageously a rotary exchanger wheel may transfer both sensible andlatent heat between fresh air and exhaust air; in this case the exhaustair stream as it is cooled may also be dried whereas the incoming freshair may be warmed as well as humidified. However, a problem with suchheat recovery ventilation equipment having a desiccant type heatexchanger wheel, is the production of frost or ice in the air permeableheat exchange matrix of the thermal wheel. During especially coldweather such as −10° C. or lower (e.g. −25° C. or lower), prior toexpelling the relatively warm exhaust air, the equipment provides forthe transfer of latent heat from the relatively warm moist exhaust airto the relatively cool dry (fresh) outside air by the use of a suitabledesiccant type heat exchange wheel. However, the cooling of therelatively moist interior air by the cold exterior air can result in theformation of ice (crystals). An uncontrolled buildup of ice within thematrix of a rotary exchanger wheel can result in decreased heattransfer, and even outright blockage not only of the exhaust air pathbut the (cold) fresh air path as well. Accordingly a means ofperiodically defrosting such a system is advantageous in order tomaintain the system's efficiency.

[0010] A defrost mechanism has been suggested wherein the fresh airintake is periodically blocked off by a damper and warm interior air isinjected, via a separate defrost air conduit, into the fresh air inletside of the fresh air path of the ventilation apparatus. However, duringthe defrost cycle, the stale inside air is still exhausted to theoutside via the exhaust air path; this is disadvantageous since byblocking only the fresh air inlet and continuing to exhaust interior airto the outside, a negative air pressure can be built up in the interiorof a building relative to the exterior atmosphere. Such a negativepressure may induce uncontrolled entry of air through any cracks andcranies in the structure of the building; the negative pressure may, inparticular, produce a backdraft effect, for oil and gas type heatingsystems, whereby exterior air may be pulled into the chimney leading tothe accumulation of gaseous combustion products in the building.

[0011] An alternate system has been suggested wherein both the fresh airinlet and exhaust air outlet are both blocked off such that warminterior air is circulated through the fresh air side of the beatexchanger element as well as through the exhaust air side of the heatexchanger element and is sent back into the building; see for exampleU.S. Pat. No. 5,193,610 the entire contents of which are incorporatedherein by reference.

[0012] It is desirable that the defrosting time period be as short aspossible and in particular not be greater than 25% of the time periodduring which a ventilation apparatus is in the ventilation configuration(e.g. if the ventilation time period is 32 minutes then desirably thedefrosting time period should not be greater than about 8 minutes).However, it has been found that adapting the technique shown in U.S.Pat. No. 5,193,610 to a rotating heat exchanger wheel by directinginterior defrost air through the defrost side of the wheel and thenreturning the air to the building by passed it through the fresh airside of the wheel while the wheel is rotating at its usual operationalor ventilation cycle rotational speed (e.g. a usual ventilation speed of15 rpm) does not produce the desired degree or efficiency of defrosting;in this case, heat which is initially taken up by the wheel from thewarm interior building air is transferred back to the interior air priorto the air being recycled to the interior of the building such that thefull heat of the interior air is not utilised for defrosting. If theusual rotational speed mentioned above is maintained, defrosting occursover a relatively significant time period (e.g. a defrost time of 18minutes or more) relative to the ventilation time period (e.g. aventilation time of 32 minutes) during which the apparatus is operating;i.e. the defrosting period may represent more than 25% of theventilation operating time which means that this defrosting technique isrelatively inefficient keeping in mind that during such defrosting, thesystem is not carrying out its primary function, namely the ventilationof a room or building.

[0013] Another problem with respect to ventilation systems comprising aheat exchanger element or core relates to the installation of anexchanger device in a building such as for example a house or other typeof building. In order for the system to operate efficiently andeffectively the outgoing exhaust air flow preferably at leastsubstantially equals the incoming fresh air flow; i.e. the exhaust andfresh air flows are preferably balanced so as to minimize or eliminateunder-pressure or over-pressure in the house relative to the outsideatmospheric pressure; a certain degree of overpressure may, however, betolerated.

[0014] Presently, such ventilation systems are balanced by means ofbalancing dampers and removeable flowmeters such as, for example, apitot tube type flow measuring device comprising a manometer to measurepressure difference; these elements must usually be installed by thebalancing technician at appropriate places in the duct work connected tothe ventilation device.

[0015] Thus, for example, one removeable flowmeter element may beinstalled in a duct on the exhaust air inlet side of the device andanother flowmeter element may be installed in a duct on the fresh airoutlet side of the ventilator device. However, the removeable flowmeterdetector elements must be temporarily installed between straight lengthsof duct of relatively sufficient length so as to be localised in arelatively stable airflow (steady state condition) and thus minimiseserroneous or misleading readings due to turbulence as may be encounteredabout an elbow or bend element of a duct. The exhaust and fresh airflows may be initially measured by placing the balancing dampersparallel to the air flow so as to present a minimum resistance to airflow. The fresh air and exhaust air flow rates may then be determinedusing the respective flowmeters. A fresh air damper may in this case beadjusted so as to reduce the fresh air flow out of the ventilator to beequal to or be up to about +5% of the exhaust air input to theventilator, i.e. as the damper is turned, so as to present a largersurface area transverse to the direction of the air flow, the flowmeteris monitored and the adjustment stopped once the flowmeter indicates aflow rate more or less equal to that of the exhaust air flowing into theventilator as initially determined.

[0016] The exhaust air flow rate into the ventilator may then beremeasured and, if necessary, (i.e. if the exhaust flow is higher thanthe fresh air input flow), the exhaust air damper may be adjusted (i.e.turned into the air flow) so as to reduce the exhaust air flow inputinto the ventilator to more or less equal the adjusted fresh air flowout of the ventilator. For example, the exhaust air flow may be adjustedso as to be somewhat smaller than the fresh air flow so as to provide aslight overpressure in the building, i.e. so as, for example, to inhibituncontrolled entry of fresh air through other parts of the building.Thereafter at least the flowmeters must be removed and replaced by thebalancing technician with appropriate duct portions. This procedure asmay be appreciated is time consuming and may take up to an hour or moreof a technician's time.

[0017] It would therefore be advantageous to have a rotating wheel heatexchanger system which can use interior air as defrost air so as todiminish or avoid the creation of a negative air pressure in thebuilding.

[0018] It would also be advantageous to have a defrostable ventulationapparatus which is of simple construction.

[0019] It would be advantageous to be able to operate a ventilationapparatus during periods of cool exterior temperature for an extendedperiod of time before having to defrost it. It would in particular beadvantageous to have a rotating wheel heat exchanger type system whichcan operate for extended periods of time during periods of cool exteriortemperatures before having to be defrosted.

[0020] It would in another aspect be advantageous to have an alternatemethod and means for balancing input and output airflow through a heatexchanger device or system.

[0021] It would in particular be advantageous to have a means ofrelatively simple construction for balancing input and output airflowthrough a heat exchanger device or system.

SUMMARY OF THE INVENTION

[0022] The present invention in a first aspect deals with the problem ofdefrosting an heat exchanger wheel while avoiding negative air pressureinducement.

[0023] Thus, in one general aspect the present invention provides amethod for defrosting a ventilation apparatus configured to transferwater moisture and sensible heat between fresh air delivered to andexhaust air taken from a building (i.e. any enclosed space) by means ofa rotating exchanger wheel defining a first air path for fresh air and asecond air path for exhaust air, said method comprising

[0024] i) directing exhaust air to flow through one of said first andsecond air paths and then through the other of said first and second airpaths back into said building, and

[0025] ii) attenuating the rotation of said exchanger wheel during adefrost cycle such that said rotary exchanger wheel is able to berelatively effectively defrosted by said exhaust air, namely, byinducing the rotary exchanger wheel to rotate at a rotational speed offrom 0 to 2 rpm (e.g. by stopping the rotation of the wheel or elseinducing an exchanger wheel rotational speed of 2 rpm or less),

[0026] Preferably, during the defrost cycle, the exhaust air is directedto flow through said second air path and then through said first airpath back into said building, and the rotation of the exchanger wheelmay be merely stopped, i.e. the wheel does not rotate during the defrostcycle.

[0027] The present invention in accordance with another general aspectprovides a defrostable ventilation apparatus, for exchanging air betweenthe interior and exterior of a building (i.e. any enclosed space), fortransferring water moisture and sensible heat between exhaust air takenfrom the building and fresh air taken from the exterior ambient air fordelivery to the building, and wherein air from the interior of thebuilding is used as defrost air to defrost the ventilation apparatus,said ventilation apparatus having fresh air path means having a freshair intake side and a fresh air discharge side, exhaust air path meanshaving an exhaust air intake side and an exhaust air discharge side,

[0028] a rotary exchanger wheel for transfer of water moisture andsensible heat between said exhaust air and said fresh air,

[0029] said exchanger wheel being configured and rotatably disposed soas to define a first air stream path and a second air stream path,

[0030] said first air stream path defining a portion of said fresh airpath means between the fresh air intake side and the fresh air dischargeside thereof and said second air stream path defining a portion of saidexhaust air path means between the exhaust air intake side and theexhaust air discharge side thereof,

[0031] a ventilation rotation component for inducing, during aventilation cycle, ventilation rotation of said exchanger wheel throughsaid fresh air path means and said exhaust air path means,

[0032] characterized in that said apparatus comprises

[0033] defrost air path means for conveying defrost air to said freshair intake side,

[0034] a damper component, said damper component being displaceablebetween a ventilation configuration

[0035] wherein said defrost air path means is closed off and said freshair intake side

[0036] and said exhaust air discharge side are open,

[0037] and a defrost configuration

[0038] wherein said fresh air intake side and said exhaust air dischargeside are closed off and said defrost air path means is open,

[0039] and

[0040] a defrost rotation component for inducing, during a defrostcycle, said rotary exchanger wheel to rotate at a defrost rotation speedof from 0 to 2 rpm through said fresh air path means and said exhaustair path means,

[0041] and wherein

[0042] during a ventilation cycle, when said damper component is in saidventilation configuration,

[0043] fresh air is able to flow through said fresh air path means andexhaust air is able to flow through said exhaust air path means,

[0044] and

[0045] during a defrost cycle, when said damper component is in saiddefrost configuration,

[0046] defrost air taken from the building, is able to circulate, fordelivery back into the building, through said exhaust air intake side,through said second air stream path, then through said defrost air pathmeans, through said first air stream path, and through said fresh airdischarge side.

[0047] It is to be understood herein that the word “building” is arefers to any enclosed space whatsoever, e.g. a one room building, amulti-room building, a room of a building and the like.

[0048] It is to be understood that as used herein the expression“ventilation cycle” refers to the time period during which theventilation apparatus operates in a ventilation mode so as to bringfresh air into the enclosed space and expel exhaust air out of theenclosed space.

[0049] It is to be understood that as used herein the expression“defrost cycle” refers to the time period during which the ventilationapparatus operates in a defrost mode wherein exhaust air is delivered tothe ventilator and expelled back into the enclosed space.

[0050] It is to be understood herein that the expression “ventilationrotation” refers to the rotation of a rotary exchanger wheel during the“ventilation cycle” during which the ventilation apparatus operates soas to bring fresh air into the enclosed space and expel exhaust air outof the enclosed space whereby an exchange of energy is effected betweenthe outgoing and ingoing air. An exchanger wheel during a ventilationcycle may, for example, have an operational or ventilation rpm(revolutions per minute) of from about 15 to about 18 rpm; i.e. for anexchanger wheel such as a Honeycomb silica gel wheel by MuntersCargoCaire, Mass. USA operable at 60 to 200 cfm; the 3A desiccantthermal wheel by Semco Inc. Miss., USA.

[0051] It is to be understood herein that the expression “defrostrotation” refers to the rotation of the rotary exchanger wheel duringthe defrost cycle at a rotation speed of from 0 to 2 rpm whereby adefrosting of the wheel may be effected by interior defrost air.

[0052] The means for attenuating or controlling the rotation of the heatexchanger wheel during a defrost cycle, depending on the systemconfiguration, must be such so as to reduce the usual operational orventilation rpm so that a defrosting of the wheel may be effected byinterior air (i.e. the operation rpm may, for example, be reduced fromabout 15 to 18 rpm to about 2 rpm or slower whereby a defrosting of anexchanger wheel may be effected); the exact attenuation or reductionnecessary to effect defrosting with interior air will of course bepredetermined on a system to system basis.

[0053] Advantageously, in terms of relatively lower cost and simplicity,the ventilation apparatus may be configured such that during the defrostcycle the exchanger wheel is stopped, i.e. the exchanger wheel has arotational speed of 0 rpm. Thus a ventilation apparatus of the presentinvention may comprise a component for stopping, during a defrost cycle,a rotary exchanger wheel from rotating.

[0054] A ventilation apparatus may, for example, comprise an electricmotor for inducing operational rotation of the exchanger wheel e.g.during a ventilation cycle. The apparatus may, for example, also includea component for stopping the rotation of the exchanger wheel in the formof an electric switch configured so as to de-energize the motor during adefrost cycle. During a defrost cycle the switch is thrown so as to cutoff the supply of electric power to the motor while during a ventilationcycle the switch is set such that electric power (i.e. current) flows tothe motor which is energized thereby. Any known suitable switch may ofcourse be used for the purpose of energizing and de-energizing themotor. The switch may, if desired, include a (known) timer mechanismsuch that after a predetermined period for the defrost cycle the switchwill be turn to the on position so as to restart the motor for aventilation cycle; the switch may of course be set up so as to manuallyturn the motor on or off, i.e. energize and de-energize the motor.

[0055] Alternatively, the component for stopping the rotation of thewheel during a defrost cycle may comprise any known type of gearingmechanism whereby the motor can be made to be engaged with or disengagedfrom the wheel for rotation or non-rotation thereof.

[0056] Alternatively as mentioned, above the rotation of the exchangerwheel may during a defrost cycle be induced to rotate at 2 rpm or less;i.e. to rotate at a relatively slower speed than the usual operationalspeed during a ventilation cycle. The mechanism whereby the rotation ofthe wheel is to be reduced but not stopped may take any desired formwhatsoever. Any known speed reducing gearing mechanism may, for example,be directly or indirectly coupled to the wheel in any suitable or knownmanner whereby the speed of rotation of the wheel may be reduced to adefrost rotation of 2 rpm or lower. If desired, instead of beingprovided with a gearing mechanism, a ventilation apparatus may beprovided with two electric motors, one being set up to run at a fixedspeed for inducing a ventilation speed rotation of the wheel (e.g. 15 to18 rpm) and the other being set up to run at a fixed speed for inducinga defrost speed rotation of the wheel (e.g. 2 rpm); during theventilation cycle the ventilation motor is energized and the defrostrotation motor is de-energized whereas during the defrost cycle thereverse is the case. Alternatively the means for inducing defrostrotation may comprise a suitably configured stepper motor, i.e. avariable speed motor.

[0057] In accordance with the present invention a defrost air path meansfor an above described apparatus may, for example, advantageously takethe form of an opening in a suitably disposed partition wall separatingthe various air paths (e.g separating said exhaust air discharge sidefrom said fresh air intake side); the damper component referred to abovemay for example block and unblock such opening depending on whether aventilation or defrost configuration is desired.

[0058] In accordance with another aspect the present invention generallyprovides a method for exchanging air between the interior and exteriorof a building, and for transferring water moisture and sensible heatbetween exhaust air taken from the building and fresh air taken from theexterior ambient air for delivery to the building, said methodcomprising

[0059] removing water moisture from exhaust air so as to obtain driedexhaust air,

[0060] transferring sensible heat from said dried exhaust air to freshair taken from the exterior ambient air so as to obtain warmed fresh airand cooled exhaust air,

[0061] exhausting said cooled exhaust air to the exterior ambient air

[0062] transferring water moisture removed from said exhaust air to saidwarmed fresh air so as to obtain humidified warmed fresh air

[0063] and

[0064] delivering said humidified warmed fresh air to the interior ofsaid building.

[0065] The above method is advantageous for use in cool weather, such asfor example when ambient air temperature is −15° C. or lower (e.g. −15°C. to −25° C.). For this method the exhaust air may be dried using afirst desiccant exchanger before it is passed through a subsequentsensible heat exchanger for additional cooling due to the transfer ofsensible heat to incoming cool fresh air. Since the air initiallyheating the incoming air is relatively dry the possibility of thesubsequent exchanger icing up may be reduced; on the other hand sincethe warmed incoming air to which the moisture is being transferred bythe first rotary exchanger has been pre-heated the possibility of thedesiccant exchanger icing up may also be reduced. This type of methodmay therefore be used for relatively longer periods of time at very coolambient air temperatures before having to revert to a defrost cycle.Advantageously, the desiccant exchanger may be configured as a rotaryexchanger wheel; any other suitable or known desiccant configuration mayhowever of course be used.

[0066] Thus in accordance with a more particular aspect the presentinvention also provides a ventilation apparatus, for exchanging airbetween the interior and exterior of a building, and for transferringwater moisture and sensible heat between exhaust air taken from thebuilding and fresh air taken from the exterior ambient air for deliveryto the building,

[0067] said ventilation apparatus comprising

[0068] fresh air path means having a fresh air intake side and a freshair discharge side,

[0069] exhaust air path means having an exhaust air intake side and

[0070] an exhaust air discharge side,

[0071] an exchanger comprising

[0072] a desiccant exchanger element for transfer of water moisture andsensible heat between said exhaust air and said fresh air,

[0073] and

[0074] a sensible heat exchanger element for transfer of sensible heatbetween

[0075] said exhaust air and said fresh air,

[0076] said desiccant exchanger element comprising a rotary exchangerwheel configured and rotatably disposed so as to define a second airstream path and a third air stream path,

[0077] said second air stream path defining a portion of said fresh airpath means and

[0078] said third air stream path defining a portion of said exhaust airpath means,

[0079] said sensible heat exchanger element comprising

[0080] a first air path defining a portion of said fresh air path meansand a fourth air path defining a portion of said exhaust air path means,

[0081] said first and second air stream paths defining respectiveportions of said fresh air path means between the intake and dischargesides of said fresh air path means,

[0082] said third and fourth air stream paths defining respectiveportions of said exhaust air path means between the intake and dischargesides of said exhaust air path means,

[0083] said fresh air path means and said exhaust air path means beingdisposed and configured such that during a ventilation cycle,

[0084] exhaust air entering the exhaust air intake side flows throughsaid third air stream path and then through said fourth air stream pathand

[0085] fresh air entering said the fresh air intake side flows throughsaid first air stream path and then through said second air stream path,

[0086] said ventilation apparatus including a rotation component forinducing rotation of said exchanger wheel through said fresh air pathmeans and said exhaust air path means.

[0087] Preferably, a desiccant wheel will have a high as possible rateof efficiency with respect to the transfer of water to the incoming coolair, e.g. 80%; lower efficiency wheels may of course be used if sodesired, keeping in mind, however, that the drier the air is, which issent to the sensible exchanger, the longer the time interval is betweendefrostings.

[0088] A sensible heat exchanger may take any known suitable formwhatsoever. A sensible heat exchanger element may, for example, compriseair-to-air heat exchanging walls between the first and fourth air paths.The sensible heat exchanger element may be of a rectangularparallelepiped shape, the first and fourth air paths thereof beingdisposed at right angles to each other; see for example U.S. Pat. No.5,002,118 wherein such a heat exchanger is shown. Such a rectangularexchanger may be disposed such that the first and fourth air paths arediagonally oriented so that they are self draining; see for example U.S.Pat. No. 5,193,610 wherein such disposition of a rectangular exchangercore is shown.

[0089] The sensible heat exchanger element if so desired may for examplebe a rotary sensible heat exchanger wheel configured and rotatablydisposed so as to define the first and fourth air stream paths. Theapparatus in this case will include a rotation component for inducingrotation of the sensible heat exchanger wheel through said fresh airpath means and said exhaust air path means.

[0090] As previously mentioned a ventilation system which includes apre-drying stage of the exhaust air and a pre-heating stage for theincoming cool fresh air may go for relatively long periods without theneed to be defrosted. Accordingly a defrost capability need notnecessarily be built into such a system. However, such a system may ifdesired include a defrost system as described herein, i.e. of theby-pass type or of the rotation speed attenuation type.

[0091] A ventilator apparatus may of course be configured such as tohave plurality of fresh air and/or exhaust air ducts each including acorresponding first and/or second air stream paths, i.e. each room in abuilding may be separately connected to the apparatus and/or theexterior of the building. Preferably, however, the apparatus is providedwith a single exhaust air path and a single fresh air path comprisingcorresponding first and second air stream paths; e.g. in this case amanifold like duct structure may deliver air from a plurality of roomsto the apparatus.

[0092] In accordance with the present invention, a defrost air pathmeans may be configured as a single defrost air path to take warmdefrost air from the exhaust air outlet side of the apparatus' exhaustair path and deliver it to the fresh air inlet side of the apparatus'fresh air path for subsequent delivery back into the building. Thus,only three distinct air paths are required in order for such anapparatus to provide both a ventilation and a defrost cycle. Moreparticularly, if such an apparatus of the present invention were, forexample, to be housed in a single cabinet, the cabinet would need onlyfour (external) openings, namely, two for the fresh air and two for thestale air; for such an example embodiment of the present invention,during the ventilation cycle, the defrost air path would be blocked andthe four openings would be in use whereas during the defrost cycle thefresh air intake and exhaust air discharge openings would be blocked,the defrost air path would be unblocked and only the remaining twoopenings would be respectively in use as inlet and outlet for thedefrost exhaust air. This type of apparatus may in this way give rise toa relatively compact ventilation heat exchange module. Although specificmention has been made to blocking off openings it is to be understoodthat blockage may occur at any suitable point along the air pathsprovided that air is able to circulate as herein described during theventilation and defrost cycles.

[0093] In accordance with the present invention a defrostableventilation apparatus may, for example, take the form of a module havinga housing or cabinet in which is disposed the various elements thereof(e.g. the air paths, dampers, airfilters, etc.).

[0094] Thus, in accordance with a more particular aspect, the presentinvention provides a ventilation apparatus wherein a fresh air pathmeans, an exhaust air path means, a rotary exchanger wheel (and ifpresent a non-rotating exchanger), and a defrost air path means, aredisposed in a cabinet, and

[0095] wherein said fresh air intake side, said exhaust air dischargeside, said fresh air discharge side and said exhaust air intake sideeach includes one respective air opening in an outer wall of saidcabinet.

[0096] A damper component for a ventilation apparatus as describedherein may take any desired form whatsoever. A damper component may forexample, comprise a first damper component and a second dampercomponent. The first damper component may be displaceable between

[0097] a ventilation configuration

[0098] wherein said defrost air path means is closed off and said freshair intake side is open and

[0099] a defrost configuration

[0100] wherein said defrost air path means is closed off and said freshair intake side is closed off

[0101] The second damper component may be displaceable between

[0102] a ventilation configuration

[0103] wherein said exhaust air discharge side is open and

[0104] a defrost configuration

[0105] wherein said exhaust air discharge side are closed off.

[0106] During a ventilation cycle, when said first and second dampercomponents are in said respective ventilation configurations,

[0107] fresh air is able to flow through said fresh air path means andexhaust air is able to flow through said exhaust air path means,

[0108] and

[0109] during a defrost cycle, when said first and second dampercomponents are in said respective defrost configurations,

[0110] defrost air taken from the building, is able to circulate, fordelivery back into the building, through said exhaust air intake side,through said second air stream path, then through said defrost air pathmeans, through said first air stream path,

[0111] and through said fresh air discharge side.

[0112] In accordance with another aspect, the present invention providesfor a defrostable ventilation apparatus, for exchanging air between theinterior and exterior of a building, for transferring water moisture andsensible heat between exhaust air taken from the building and fresh airtaken from the exterior ambient air for delivery to the building, andwherein air from the interior of the building is used as defrost air todefrost the ventilation apparatus, said ventilation apparatus having

[0113] fresh air path means having a fresh air intake side and a freshair discharge side, exhaust air path means having an exhaust air intakeside and an exhaust air discharge side,

[0114] a rotary exchanger wheel for transfer of water moisture andsensible heat between said exhaust air and said fresh air,

[0115] said exchanger wheel being configured and rotatably disposed soas to define a first air stream path and a second air stream path,

[0116] said first air stream path defining a portion of said fresh airpath means between the fresh air intake side and the fresh air dischargeside thereof and said second air stream path defining a portion of saidexhaust air path means between the exhaust air intake side and theexhaust air discharge side thereof,

[0117] and

[0118] a rotation component for inducing rotation of said exchangerwheel through said fresh air path means and said exhaust air path means,

[0119] characterized in that said apparatus comprises

[0120] defrost air path means for providing an air path by-passing saidfirst air steam path, said defrost air path means comprising a defrostair discharge side and being configured to connect the exhaust airdischarge side with the defrost air discharge side thereof for conveyingdefrost air to said defrost air discharge side from said exhaust airdischarge side,

[0121] and

[0122] a damper component, said damper component being displaceablebetween a ventilation configuration for a ventilation cycle

[0123] wherein said defrost air path means is closed off and said freshair intake side

[0124] and said exhaust air discharge side are open,

[0125] and a defrost configuration for a defrost cycle

[0126] wherein said fresh air intake side and said exhaust air dischargeside are closed off and said defrost air path means is open,

[0127] and wherein

[0128] during a ventilation cycle, when said damper component is in saidventilation configuration,

[0129] fresh air is able to flow through said fresh air path means andexhaust air is able to flow through said exhaust air path means,

[0130] and

[0131] during a defrost cycle, when said damper component is in saiddefrost configuration,

[0132] defrost air taken from the building, is able to circulate, fordelivery back into the building, through said exhaust air intake side,through said second air stream path, then through said defrost air pathmeans, and through said defrost air discharge side.

[0133] As may be appreciated from the above, this other aspect of thepresent invention provides for the possibility of not having to adjustthe speed of the rotating wheel for the purposes of a defrost cycle;speed adjustment could of course still be done if desired. Forsimplicity, however, the wheel may be allowed to continue to rotate at aspeed which is normal for a ventilation cycle. In this case, since thedefrost air is made to by-pass the fresh path defined by the rotatingexchanger wheel the defrost air does not take heat back from the wheelprior to being returned to the building; in this way the possibilitythat the wheel may lose heat back to the defrost air sent back to thebuilding is avoided.

[0134] In accordance with a by-pass type apparatus as described hereinthe defrost air path means may have its own independent outlet side fordischarging air back to the building. Alternatively, the defrost airpath means may not have such an independent outlet but may be coupled tothe fresh air discharge side of the fresh air path means, i.e. aseparate discharge opening for the returning air may be avoided. Thus adefrost air path means for providing an air path by-passing the firstair steam path may be configured to connect the exhaust air dischargeside with the fresh air discharge side for conveying defrost air to saidfresh air discharge side from said exhaust air discharge side. In thislater case, during a defrost cycle, when the damper component is in saiddefrost configuration, defrost air taken from the building, is able tocirculate, for delivery back into the building, through said exhaust airintake side, through said second air stream path, then through saiddefrost air path means, and through said fresh air discharge side.

[0135] In accordance with a further general aspect the present inventionprovides a method for balancing fresh air and exhaust air flow throughan operating ventilation apparatus, said ventilation apparatus beingconfigured for exchanging air between the interior and exterior of abuilding (i.e. any enclosed space) and for transferring, a member of thegroup comprising i) sensible heat and ii) sensible heat and watermoisture, between exhaust air taken from the building and fresh airtaken from the exterior ambient air for delivery to the building,

[0136] said ventilation apparatus comprising

[0137] fresh air path means having a fresh air intake side and a freshair discharge side, exhaust air path means having an exhaust air intakeside and an exhaust air discharge side,

[0138] an air-to-air exchanger body for exchanging, a member selectedfrom the group comprising i) sensible heat and ii) sensible heat andwater moisture, between fresh air and exhaust air, said exchanger bodybeing configured and disposed so as to define a first air stream pathand a second air stream path,

[0139] said first air stream path defining a portion of the fresh airpath means between the fresh air intake side and the fresh air dischargeside thereof and said second air stream path defining a portion of saidexhaust air path means between the exhaust air intake side and theexhaust air discharge side thereof,

[0140] said method comprising

[0141] determining a first static pressure difference in said fresh airpath means, said first static pressure difference being determined withrespect to first and second static pressure sampling locations, saidfirst air stream path being disposed between said first and secondstatic pressure sampling locations,

[0142] determining a second static pressure difference in said exhaustair path means, said second static pressure difference being determinedwith respect to third and fourth static pressure sampling locations,said second air stream path being disposed between said third and fourthstatic pressure sampling locations,

[0143] comparing predetermined air flow values represented by each ofsaid so obtained first and second pressure differences so as todetermine if said predetermined fresh air and exhaust air flow valuesare at least substantially the same.

[0144] In accordance with the above described balancing method theventilation apparatus may include

[0145] a first adjustable damper component for adjusting air flowthrough the fresh air path means, and

[0146] a second adjustable damper component for adjusting air flowthrough the exhaust air path means.

[0147] If desired, however, such first and second adjustable dampercomponents may as mentioned above be provided by the ductwork of thebuilding to which the ventilator is connected or if desired or necessarybe temporarily and removeably inserted in the duct work by the balancingtechnician; in the latter case once balance is achieved the damper meansare removed and replace with suitable duct pieces.

[0148] The balancing method of the present invention may, thus, forexample, include manipulating at least one of said first and seconddamper components so that said so obtained first and second pressuredifferences are each set at a value whereby each pressure differencerepresents a respective predetermined air flow value which is at leastsubstantially the same as the predetermined flow value of the other.

[0149] The air flow values may be predetermined as shall be explainedbelow. The predetermined flow values may for example be arranged as flowinput and output charts set forth by way of example below as charts Iand II respectively; the flow values may of course be presented in anyother desired fashion. The predetermined air flow values for variousstatic pressure differences shown in the charts below may be consultedduring balancing of an apparatus; the charts may for example be fixed toan appropriate surface of the apparatus for consultation by a technicianbalancing the apparatus. In the charts ▴P is the static pressuredifference. CHART I FRESH AIR ▴P Flow rate (inches water) (cfm) 0.01 80.02 16 0.03 24 0.04 32 0.05 40 0.06 48 0.07 56 0.08 64 0.09 72 0.1 800.11 88 0.12 96 0.13 104 0.14 112 0.15 120 0.16 128 0.17 136 0.18 144

[0150] CHART II EXHAUST AIR ▴P Flow rate (inches water) (cfm) 0.02 70.04 14 0.06 21 0.08 27 0.1 34 0.12 41 0.14 48 0.16 55 0.18 62 0.2 680.22 75 0.24 82 0.28 96 0.3 103 0.32 110 0.34 116 0.36 123 0.38 130 0.4137 0.42 144

[0151] In accordance with a further aspect, the present inventionprovides an additional type of ventilation apparatus, for exchanging airbetween the interior and exterior of a building (i.e. any enclosedspace), and for transferring, a member of the group comprising i)sensible heat and ii) sensible heat and water moisture, between exhaustair taken from the building and fresh air taken from the exteriorambient air for delivery to the building, said ventilation apparatuscomprising

[0152] fresh air path means having a fresh air intake side and a freshair discharge side,

[0153] exhaust air path means having an exhaust air intake side and anexhaust air discharge side,

[0154] exchanger means for exchanging, a member selected from the groupcomprising

[0155] i) sensible heat and ii) sensible heat and water moisture,between fresh air and exhaust air, said exchanger means being configuredand disposed so as to define a first air stream path and a second airstream path,

[0156] said first air stream path defining a portion of the fresh airpath means between the fresh air intake side and the fresh air dischargeside thereof and said second air stream path defining a portion of saidexhaust air path means between the exhaust air intake side and theexhaust air discharge side thereof,

[0157] characterized in that said apparatus comprises

[0158] first, second, third and fourth static pressure taps,

[0159] said first and second static pressure taps being configured anddisposed for the determination of a first static pressure differencetherebetween in said fresh air path means, said first air stream pathbeing disposed between said first and second static pressure taps,

[0160] said third and fourth static pressure taps being configured anddisposed for the determination of a second static pressure differencetherebetween in said exhaust air path means, said second air stream pathbeing disposed between said third and fourth static pressure taps.

[0161] In accordance with the present invention a ventilation apparatusmay advantageously comprise first adjustable damper component foradjusting air flow through the fresh air path means, and a

[0162] second adjustable damper component for adjusting air flow throughthe exhaust air path means; the presence of such dampers in theventilator itself will eliminate the necessity of the balancingtechnician from having to install dampers and remove them as necessary.

[0163] In accordance with the present invention, the static pressuretaps may be configured in any desired manner whatsoever, provided thatthey facilitate the taking of static pressure readings; e.g. thepressure is measured near the wall of the duct means defining an airpath, i.e. the pressure connection terminates at least substantiallyflush with the wall of the duct means defining the air path.

[0164] In accordance with the present invention the exchanger means fora balanceable ventilation apparatus may take any desired form. Theexchanger means may for example take the form of one or more(air-to-air) rotary and/or stationary exchanger cores or elements suchas described herein. Thus, the exchanger means may comprise an exchangerbody such as, for example, a rotary exchanger wheel or box like parallelchannel exchanger as described above.

[0165] In accordance with the present invention the first adjustabledamper component may for example, disposed on the fresh air dischargeside of the fresh air path means, and the second adjustable dampercomponent may be disposed on the exhaust air intake side of the exhaustair path means.

[0166] The first and second static pressure taps may each comprise astatic pressure sampling aperture defined by a wall of the fresh airpath means and the third and fourth pressure tap means may each comprisea static pressure sampling aperture defined by a wall of the exhaust airpath means.

[0167] The ventilation apparatus may be configured as a constant flowventilation apparatus; i.e. an apparatus wherein during the ventilationand defrost cycles the air flow is intended to be more or less constant(i.e. not be manipulated up or down).

[0168] For a balanceable ventilation apparatus the fresh air path means,the exhaust air path means, and the heat exchanger body may be disposedin a cabinet, wherein said fresh air intake side, said exhaust airdischarge side, said fresh air discharge side and said exhaust airintake side each includes one respective air opening in an outer wall ofsaid cabinet, wherein said first and second pressure taps each comprisea pressure sampling aperture defined by a wall of said fresh air pathmeans and wherein said third and fourth pressure taps each comprise apressure sampling apertures defined by a wall of said exhaust air pathmeans. In accordance with the present invention, the fresh air pathmeans comprises a wall of said cabinet which defines said apertures ofsaid first and second pressure tap means, and

[0169] the exhaust air path means comprises a wall of said cabinet whichdefines said apertures of said third and fourth pressure tap means.

[0170] For any ventilation apparatus as described herein fan means formoving air through the air paths thereof may be disposed outside theapparatus (i.e. the fans may form part of the overall ventilationductwork of the building). Alternatively, fan means may be integratedwithin a ventilation apparatus itself, the latter being preferred; i.e.a ventilation apparatus may be configured such that the fresh air pathmeans includes a fan for moving fresh air through said fresh air pathmeans and the exhaust air means includes a fan for moving exhaust airthrough said exhaust air path means, such fans forcing air to passthrough the first and second air stream paths. A ventilation apparatus,for example, may comprise a blower assembly having motor(s), blowerwheels, blower housings, etc . . . . The blower assembly may have asingle motor; two blower wheels may in this case be mounted directly onthe shaft of such motor. The blower assembly may also include separateblower housings for each of the blower wheels, with one blower wheelbeing disposed in each of the fresh air and exhaust air paths. Thus forexample, an above described apparatus may include a fan mounted in anabove mentioned cabinet for moving fresh air through said fresh air pathmeans and for moving exhaust air through said exhaust air path means,said fan comprising one motor and two blower wheels operativelyconnected thereto, said fresh air path means including one said blowerwheel and said exhaust path means including the other said blower wheel.The ventilation apparatus may of course include a separate motor for thefresh air and for the exhaust air blower assembly.

[0171] Any ventilation apparatus may also be provided with air filtersfor each of the air paths.

[0172] Any ventilator of the present invention may, for example, asdesired or necessary, be provided with one or more of exchanger elementsor cores such as previously described herein. Desiccant wheels which maybe used include those for example sold by Munters CargoCaire or Semco asmentioned previously. Sensible heat wheels which may be used includethose for example sold by Semco Inc. Sensible non-rotating heat exchangecores which may be used include those as described in the abovementioned patents.

[0173] The nature and construction of the various elements of anapparatus in accordance with the present invention will of course dependon the volumes of air it is desired to handle and the heat recoveryefficiency.

[0174] In accordance with the present invention a ventilation apparatusmay, if desired, include both defrosting means and air flow balancing asdescribed herein.

[0175] Keeping the above in mind, the present invention will beparticularly describes by reference to the accompanying drawings whichillustrate example embodiments of the present invention.

DESCRIPTION OF THE DRAWINGS

[0176]FIG. 1 is a schematic perspective view of a cabinet comprising aventilation apparatus, in accordance with the present invention, whichincludes both defrosting means and means for balancing air flow;

[0177]FIG. 2 is a schematic perspective view of the cabinet of theapparatus shown in FIG. 1 but with the top cover wall and the front doorremoved and the interior components not shown;

[0178]FIG. 3 is a schematic front view showing the air paths of theventilation apparatus of FIG. 1 when the apparatus is in a ventilationconfiguration for a ventilation cycle (only the rotary exchanger wheelis shown in place);

[0179]FIG. 4 is a schematic front view showing the air paths of theventilation apparatus of FIG. 1 when the apparatus is in a defrostconfiguration for a defrost cycle (only the rotary exchanger wheel isshown in place);

[0180]FIG. 5 is a top view of the apparatus shown in FIG. 1 but whereinthe top outer wall of the apparatus has been removed;

[0181]FIG. 6 is a front view of the ventilation apparatus shown in FIG.1 with the front door of the cabinet removed;

[0182]FIG. 7 is a sectional view along line 7-7 of FIG. 5;

[0183]FIG. 8 is the same view as shown in FIG. 7 but with a portion of apartition wall means separating the exhaust outlet side from the freshair inlet side being partially cut away;

[0184]FIG. 9 is a schematic drawing of the exhaust air blower housingand blower wheel of the apparatus of FIG. 1 illustrating a combinationdamper/wall element for directing exhaust air flow on the exhaust sideof the exhaust air path means and means for displacing the damper/wallelement and a fresh air inlet damper so as to control exhaust and freshair flow;

[0185]FIG. 10 is a schematic view of a motor/rod means for displacingthe damper/wall element and the fresh air damper shown in FIG. 9 betweena ventilation and defrost position;

[0186]FIG. 11 schematically shows another embodiment of the presentinvention similar to that shown in FIG. 6 but wherein a second motor isprovided to urge rotation of the exchanger wheel at a lower defrostrotation speed than the ventilation speed;

[0187]FIG. 12 is a schematic perspective view of a prior art setup forbalancing a ventilation apparatus connected to the ductwork of abuilding;

[0188]FIG. 13 is a schematic perspective view of a manometer for takingpressure difference readings; FIG. 14 is schematic illustration of thesame view as shown in

[0189]FIG. 8 but with the front door in place showing the disposition ofpressure taps on either side of the exchanger wheel, the front doorbeing partially cut away and this figure appearing on the same sheet ofdrawings as FIG. 5;

[0190]FIG. 15 is a sectional view along line 15-15 of FIG. 5;

[0191]FIG. 16 is a sectional view along line 16-16 of FIG. 5;

[0192]FIG. 17 is a partial schematic view of the front door of theapparatus of FIG. 1 showing in section an example pressure tap openingpassing through the door;

[0193]FIG. 18 is a partial schematic view of the inner side of the frontdoor of the apparatus of FIG. 1 showing the mouth of the pressure tapopening shown in FIG. 17;

[0194]FIG. 19 is a partial schematic view of the front door of theapparatus of FIG. 1 showing in section an alternate bevelled pressuretap opening configuration passing through the door;

[0195]FIG. 20 is a partial schematic view of the inner side of the frontdoor of the apparatus of FIG. 1 showing the mouth of the pressure tapopening shown in FIG. 19;

[0196]FIG. 21 is a schematic illustration of an arrangement fordetermining the predetermined pressure co-related calibration air flowsfor an apparatus shown in FIG. 1

[0197]FIG. 22 is a schematic illustration of an arrangement forbalancing the air flow for an apparatus shown in FIG. 1 connected to theduct work of a building (not shown);

[0198]FIG. 23 is a schematic illustration of an arrangement forbalancing the air flow for a ventilation apparatus shown having arectangular exchange core connected to the duct work of a building (notshown);

[0199]FIG. 24 is a schematic illustration of a ventilation apparatuscomprising a desiccant wheel and a rectangular sensible heat exchanger;

[0200]FIG. 25 is a schematic illustration of a ventilation apparatus asshown in FIG. 8 adapted to include a sensible heat exchanger along witha desiccant type rotary wheel;

[0201]FIG. 26 is a general schematic illustration of an example of adefrostable ventilation apparatus using a by-pass technique for theapparatus;

[0202]FIG. 27 is a schematic illustration of an example of a by-passdefrostable ventilation apparatus exploiting elements common with theapparatus shown in FIGS. 1 to 10.

[0203] In the drawings like reference characters indicate correspondingparts in the different figures.

DETAILED DESCRIPTION

[0204]FIG. 1 shows a ventilation apparatus of the present inventionwhich includes both a defrost means and air flow balancing means.

[0205] The apparatus shown in FIG. 1 includes a cabinet indicatedgenerally by the reference number 1. The cabinet 1 is preferablyprovided with insulated walls and partition wall members.

[0206] The cabinet 1 has a top outer wall 2 and a front door 3. The door3 is of composite construct comprising a sheet metal outer element 4 andan inner element 5. The inner element 5 is of sheet foam material and issized to cover the entire inner surface of the element 4. The foamelement 5 acts to provide an airtight seal for the door along itsperiphery adjacent the other walls of the cabinet; element 5 also actsas a heat insolation member. Although not shown, the door may behingedly attached to hinge members and may be kept shut for example bysnap locking members which cooperate with members on the door; see forexample U.S. Pat. No. 5,193,610.

[0207] The cabinet 1 is provided with pressure tap openings 6, 7, 8, and9; their function will be discussed below with respect to the air flowbalancing aspect of the apparatus.

[0208] Turning to FIG. 2 the cabinet 1 is shown with the top 2 and frontdoor 3 removed; the interior ventilation elements are also not shown inorder to better illustrate the major partitioning wall members of thecabinet which generally define the fresh air and exhaust air paths. Thecabinet 1 is provided with four end wall openings, namely wall openings10, 11, 12 and 13; a pair of wall openings being disposed in opposed endwalls 14 and 15. As may be seen the opening 10 and 11 are more or lessdisposed such that opening 10 is vertically in line with and aboveopening 11. Opening 12 on the other hand is disposed so as to beadjacent the door 3 whereas the opening 13 is rearwardly disposedadjacent the rear wall of the cabinet 1; i.e. openings 12 and 13 are notvertically aligned.

[0209] Referring back to FIG. 1, duct connector members 20 and 21 aredisposed about respect openings 10 and 11. Each of these duct connectormembers is provided with respective adjustable circular plate damperelements 22 and 23. The adjustable damper elements 22 and 23 are eachconfigured and pivotally disposed such that each may be manually rotatedabout a vertical axis between a closed position wherein the majorsurfaces of the damper are perpendicular to the air flow (i.e. theopenings 10 and 11 are essential closed off) and a fully open positionwherein the dampers are disposed such that the major surfaces areparallel to the air flow, i.e. the air hits the damper elements edgewisesuch that the openings 10 and 11 are essentially not obstructed thereby.In FIG. 1 the damper elements are shown in edgewise disposition withrespect to the flow of air. These adjustable damper elements may be usedto balance fresh and exhaust air flow through the ventilator apparatusas shall be discussed below. Although the ventilation apparatus is shownwith these damper elements 22 and 23 they may if desired not be part ofthe apparatus as shown and thus not be present. In this case, however,if desired the adjustable damper elements may form part of the overallduct work to which the apparatus is ultimately to be connected to inorder to facilitate airflow balancing as shall be discussed below.

[0210] Turning back to FIG. 2, the cabinet is provided with alongitudinally extending central partitioning member 25. Thispartitioning member 25 along with the exterior walls of the cabinet(including the front door 3) partition the interior of the cabinet 1into an upper interior half and a lower interior half The upper interiorhalf of the cabinet, with the door 3 in place, defines the fresh airpath means for the fresh air; i.e. during a ventilation cycle, fresh airmay enter opening 12 and exit opening 10 as shown by the air flow arrow26. The lower half of the cabinet, again with the door 3 in place,defines the exhaust air path means for the exhaust air; i.e. during aventilation cycle, exhaust air may enter opening 11 and exit opening 13as shown by the air flow arrow 27.

[0211] The partitioning member 25 is also provided with opening 30, 31and 32.

[0212] The opening 30 is present so as to accommodate a rotary exchangerwheel such that approximately half of the wheel will project into eachof the lower and upper interior halves of the cabinet.

[0213] Referring briefly to FIGS. 15 and 16, a pair of opposed bafflemembers 35 and 36 are disposed on respective sides of the rotaryexchanger wheel 37 in the upper interior half of the cabinet and a pairof baffle members 38 and 39 are disposed on respective sides of therotary exchanger wheel 37 in the lower interior half of the cabinet. Thebaffle members 35, 36 and 38 and 39 serve to channel air in the upperand lower interior halves of the cabinet essentially solely throughrespective upper and lower semi-circular portions 37 a and 37 b of wheel37 which extends into the upper and lower interiors of the cabinet 1;the axis of rotation of the wheel lies more or less parallel to andpasses through the partition member 25. These baffles may also be seenfor example in FIGS. 4 and 5.

[0214] A single heat exchange element or (heat recovery) core 37 isshown in the figures as being suitably mounted in the cabinet 1.Although one such core 37 is shown it will nevertheless be appreciatedthat two or more such cores may, if desired, be used either in series orin parallel, provided that appropriate modifications are made to thepartitioning members so as to accommodate the required air flowpatterns.

[0215] Referring back to FIG. 2, the opening 31 is configured so as toseat an electric blower motor such that the motor is disposed in theupper interior half of the cabinet and allow at least the shaft of theblower motor to extend therethrough so as to engage a blower wheeldisposed in a lower blower housing.

[0216] The opening 32 is present so as to provide for air communicationbetween the upper and lower interior halves of the cabinet during adefrost cycle.

[0217] Referring now to FIGS. 3 and 4, these show, in a generalschematic manner, the disposition of the flow of air through the rotaryheat exchange element or core 37 of the apparatus of FIG. 1 during theventilation and defrost cycles.

[0218]FIG. 3 illustrates the air paths when the apparatus is operatingin a ventilation cycle.

[0219]FIG. 4 illustrates the air path when the apparatus is operating ina defrost cycle.

[0220] As seen in FIGS. 3 and 4 the apparatus has additional ductconnector members 40 and 41 which are disposed about respect to openings12 and 13. The duct connector member 40 is provided with a circularplate damper elements 42; this damper element may be urged to block offor open the opening 12 in a manner similar to the operation of damperelements 22 and 23 mentioned above. The damper element 42 is configuredand pivotally disposed such that it may be rotated by a motor (as shallbe explained below) about a vertical axis between a closed positionwherein the major surfaces of the damper are perpendicular to the airflow (i.e. the opening 12 is essential closed off) and a fully openposition wherein the damper element 42 present an edge to the air flow.

[0221] As may be seen from FIG. 4, the opening 32 in the partitionmember is open or unobstructed and the exhaust air may flow back throughthe upper portion 37 a of the wheel for return to a building. On theother hand, in FIG. 3 the opening 32 in the partition member 25 is shownas being blocked off by a suitably configured and sized damper element43 such that the exhaust air is directed out of opening 13. Thus damperelement 43 is shown in FIG. 3 in a ventilation configuration and in FIG.4 in a defrost configuration. The apparatus is provided with a lowerblower assembly having a blower housing (not shown) which communicateswith the opening 13 for the expulsion of exhaust air via a shortchannel; a lower wall part of this short channel is designated by thereference numeral 45 in FIGS. 3 and 4. The damper element 43 is suitablypivoted along one edge such that it may pivot downwardly into a defrostposition or configuration as shown in FIG. 4; i.e. the damper element 43is pivotally connected in any suitable or desired fashion at edge 46 soas to be able to be displaceable between the ventilation and defrostconfigurations (e.g. by a pin and sleeve combination such as used for adoor hinge). The damper element 43 is suitably configured and sized suchthat when it is in the defrost configuration shown in FIG. 4 the damperelement 43 leaves open, opening 32, but blocks off the air path definedby the above mentioned short channel such that exhaust air is not ableto flow to the opening 13. During the defrost cycle the damper element42 blocks off the fresh air path communicating with the opening 12.

[0222] Although FIG. 3 shows an interior opening 32 for connecting theupper and lower interior portions of the cabinet, the opening may ifdesired be configured as a channel which is defined on the outside ofthe cabinet and which is connected thereto through suitable openings onthe walls defining the lower and upper interior portions of the cabinet.In this case the damper element 43 would have to be suitablyreconfigured to be able to block off or open this outside channel.

[0223] The apparatus of FIG. 1 as shown in FIGS. 3 and 4 has a total ofthree possible unobstructed air paths. The air paths in use depend onthe operating cycle of the apparatus. There are two air paths during aventilation cycle, namely a fresh air path and an exhaust air path. Onthe other hand, there is one air path during the defrost cycle, namelythe air path whereby defrost interior air is able to flow or circulatethrough the lower and upper interior parts of the apparatus for deliveryback into a building.

[0224] Thus, in the ventilation configuration shown in FIG. 3 there aretwo main air path elements, namely the air paths designated by the airflow arrows 26 and 27. The air path defined by the arrows 26 deliversfresh air to the heat recovery core portion 37 a and delivers fresh airwhich has passed through the heat recover core portion 37 a to theinterior of the building. The air path defined by the arrows 27 on theother hand delivers exhaust or stale air from a building to the heatrecovery core portion 37 b and exhausts, to the exterior of thebuilding, the stale air which has passed through the heat recover coreportion 37 b.

[0225] Referring to FIG. 4 the apparatus is illustrated as being in adefrost configuration having a defrost air path designated by the airpath arrows 27 a. In the configuration of FIG. 4 no fresh air isintroduced into the building and building air is allowed to circulatethrough the upper and lower portions 37 a and 37 b of the wheel 37 fordelivery back to the interior of the building; in this way the wheel 37may be defrosted without inducing any substantial negative air pressurein the building.

[0226] Referring now to FIGS. 5, 6, 7, 8 and 14, these figuresschematically show the apparatus of FIG. 1 in a ventilationconfiguration for a ventilation cycle as illustrated in FIG. 3.

[0227]FIG. 5 shows the apparatus of FIG. 1 wherein the top upper wallhas been removed so as to generally expose in more detail the ventilatorelements of the upper interior half of the cabinet. Thus can be seen ablower housing 50, a blower wheel 51 disposed in the housing 50, a(fresh) air inlet opening 52 in the blower housing 50 disposed below theblower wheel 51, and a motor shaft portion 53 to which the blower wheel51 is attached.

[0228] As seen from FIGS. 5, 6, 7, 8 and 14, a support bracket 55 isfixed to and extends perpendicularly down from the top wall 2. A motor56 is fixed to the bracket 55. The motor 56 has a shaft 57 which isfixed to a rocker or actuation arm means 58 (here, by way of example, inthe form of a circular plate). The rocker arm means rotatably engagesone end of rods 60 and 61; i.e. bent over ends of the rods 60 and 61 arerotatably engaged by respective openings in the rocker arm means 58. Theother end of rod 60 is hingedly attached to the damper element 43; theother end of the rod 61 is similarly rotatably/hingeably attached to thedamper element 42. As illustrated the rods and corresponding damperelements are in a ventilation configuration. Rotation of the rocker armmeans 58 by the motor 56 will cause the rods to pull/push the damperelements into respective defrost configurations; a more detailedexplanation will be provided below with respect to FIGS. 9 and 10.

[0229] The blower housing 50 has a lateral (fresh) air outlet opening 62(see FIGS. 7 and 8).

[0230] The upper interior half of the cabinet 1 includes a motor 65.

[0231] The lower interior half of the cabinet 1 includes a blowerhousing 66, a blower wheel 67 disposed in the housing 66, an (exhaust)air inlet opening 68 in the blower housing 66, and a motor shaft portion69 to which the blower wheel 67 is attached. As may be seen the twoblower wheels 51 and 67 are disposed on opposite sides of the motor 65and are mounted directly on corresponding shaft portions 53 and 69 ofthe shaft of the motor 65.

[0232] The blower housings 50 and 66 may be made of an expandedpolystyrene material.

[0233] The motor 65 is seated in opening 31 in the partitioning member25. The opening 31 is large enough to allow an end of the motor to passpartway therethrough but is provided with a shoulder rim 70 sized tostop or impede the passage of the motor into the interior of the housing66; if desired or necessary, however, any suitable sealing gasket meansmay be disposed around the motor (and shaft 69) in the hole 31 so toprovide an airtight seal. The motor 65 is rigidly joined to the shoulder70 of opening 31 by a suitable fixation means (such as nut/bolt means72). The ceiling of the blower housing 66 as may be appreciated isdefined by a portion of the partition member 25. Reference will now bemade to FIGS. 9 and 10. As mentioned above the damper members orelements 42 and 43 are displaced between respective ventilation anddefrost configurations by means of a motor and rod arrangement; themotor-rod arrangement may take a form analogous to that of the motor-rodassembly shown in FIG. 2c of U.S. Pat. No. 5,193,610. Thus, themotor-rod arrangement includes a spring member for biasing the dampermembers or elements 42 and 43 in one configuration, the motor 56 beingused to displace the damper members or elements to the otherconfiguration.

[0234]FIG. 9 shows the lower blower housing 66 with the ceiling asdefined by the partition member 25 removed so as to expose the blowerwheel 67. As shown the damper member 43 is shown in place pivotableabout edge 46; as shown the damper 43 is configured and disposed so asto block opening 32; the damper 43 is however also configured and sizedsuch that if it is pivoted downwardly into the short channel memberconnecting the housing 66 to the opening 13 the short channel member isblocked and exhaust air is free to circulate upwardly through theunobstructed opening 32 into the upper interior part of the cabinet.

[0235] Referring to FIG. 10 the motor-rod assembly is shown in moredetail. Thus the motor 56 has a shaft 57 which is fixed to rocker armmeans 58; the motor is fixed to the bracket 55 in any suitable manner;the bracket 55 in turn is suitably fixed to the top wall 2. One end ofthe rod 60 has a bent over end 75 which is rotatably disposed in a holein the rocker arm means 58 while the other end of rod 60 has a loopmember which is hingedly fixed to the damper element 43. One end of therod 61 has a bent over end 76 which is also rotatably disposed in a holein the rocker arm means 58 while the other end of rod 61 has a bent overend 77 which is similarly rotatably fixed to damper element 42; i.e. viaa small plate/hole member fixed to the damper member. A spring member(not shown) in the form of a (helical) coil spring is disposed aroundthe shaft 57; one end of the coil spring is fixed with respect to themotor and the other end is fixed to the actuating or rocker arm means 58so as to bias the damper members 42 and 43 with respect to a respectiveventilation configuration. Activation and deactivation of the motor 56will thus cause the dampers 42 and 43 to be displaced between theventilation and defrost configurations. Any suitable motor (such as forexample a synchronous motor as made by Hansen Manufacturing Company,Inc.) may for example be used for this purpose. Any other suitabledamper mechanism may of course be used, keeping in mind that the purposeof the damper is to block off the appropriate air path for theventilation cycle and the defrost cycle while leaving the othernecessary air paths unobstructed.

[0236] Referring back to FIGS. 6, 7 and 8, the exchanger wheel 37 may bea desiccant type exchanger wheel for transferring sensible heat andwater moisture between air streams. The exchanger wheel 37 isrotationally supported in the interior of the cabinet 1 in any knownmanner so as to be able to effect an exchange of sensible and latentheat between fresh air and exhaust air; i.e. in the latter case anexchange of water moisture. Thus, the exchanger wheel 37 has an axlemember 78; the axle member 78 is supported by suitable bearing members79 a and 79 b such that the axle 78 is more or less parallel to thepartition member 25. The bearing members 79 a and 79 b facilitaterotation of the rotary exchanger 37 through the upper and lower halvesof the interior of the cabinet. The first air stream path mentionedabove is defined by a plurality of parallel channels in the upperportion 37 a of the exchanger wheel one of which is shown designated bythe reference number 80; similarly the second air stream path mentionedabove is also defined by a plurality of parallel channels in the lowerportion 37 b of the exchanger wheel one of which is shown designated bythe reference number 81. These channels in the example wheel shown areparallel to the axle 78. The open ends of the channels of the upper andlower portions of the wheel 37 may be seen in FIGS. 15 and 16; the wheelis in other words permeable to air along the axis of rotation thereof.As can be appreciated as the wheel 37 rotates a channel initiallydefining a portion the first air stream path will eventually define aportion of the second air stream path and so on.

[0237] Referring to FIG. 6, rotation of the wheel 37 is induced by themotor 84 which turns a shaft 85. The shaft 85 in turn rotates a pulleybody 86 which engages a belt 87. The belt 87 surrounds a substantialpart of the periphery of the wheel 37 and engages the exterior surfaceof the wheel 37 sufficiently such that it induces the wheel 37 to rotateabout the above mentioned axle 78 in response to rotation of the shaft85.

[0238] In FIG. 8, the apparatus as previously mentioned is shown asbeing in a ventilation configuration. In this configuration, during aventilation cycle the fan means operate such that:

[0239] exhaust air will proceed from the opening 11 into the lower leftair pocket 88 (i.e. the exhaust air intake side of the exhaust air pathmeans of the ventilation apparatus) in the direction of the arrow 27;the exhaust air will then pass through the parallel channels 81 of therotating core into the lower right air pocket 89 in the direction of thearrow 27; the exhaust air will pass through the opening 68 of theexhaust blower housing 66 and into the air pocket 89 a defined by thepreviously mentioned short channel (i.e. the exhaust air discharge sideof the exhaust air path means of the ventilation apparatus) and thenceto be ejected out of opening 13 as seen by arrow 27.

[0240] fresh air will proceed from through the opening 12 into the rightupper air pocket 90 (i.e. the fresh air intake side of the fresh airpath means of the ventilation apparatus) in the direction of the arrow26; the fresh air will then pass through the opening 52 of the fresh airblower housing 50 through the outlet opening 62 into the channels 80;the fresh air will then pass through the upper portion 37 a of the wheel37 into the left upper air pocket 91 (i.e. the fresh air discharge sideof the fresh air path means of the ventilation apparatus) and out of theopening 10 in the direction of the arrow 26 for delivery to the interiorof the building.

[0241] If a defrost cycle is desired the arm means 58 is rotated by themotor 56 so as to descend the damper element 43 so as to open or unblockthe opening 32 while at the same time blocking off the exhaust airoutlet opening 13; i.e. the damper element 43 is displaced so as toconnect the air pockets 89 a and 90. At the same time the damper element42 is rotated so as to block off the fresh air inlet opening 12. Theinterior air of the building can then circulate through the upper andlower portions of the wheel 37 so as to effect a defrost of the wheel.Thus, during a defrost cycle, the interior defrost air may circulatethrough portions of both of the fresh air and exhaust air paths of thedefrostable ventilation apparatus for delivery back into the building,i.e. the warm interior air may be confined to circulate from theinterior of the building into the ventilation apparatus and back to theinterior of the building.

[0242] During the above described ventilation cycle the motor 84 will beenergized so as to induce ventilation rotation of the wheel 37 (e.g. arotation of about from 15 to 18 rpm). During the defrost cycle, however,the rotation of the wheel 37 is stopped by switching off the current tothe motor by means of an electric switch shown in FIG. 6 by way of ablock element, the switch being connectable to a source of electricenergy shown in dotted outline. Turning the switch on or off will effectenergizing and de-energizing of the motor 84 as desired. Any switchsuitable for the purpose may of course be used. During the ventilationand defrost cycles the blower motor is of course in an energized stateso as to urge air through the apparatus. It has for example been foundthat with an exterior air temperature of −15° C. and a ventilation cycletime period of 32 minutes, that the defrost time may be 6 minutes withthe wheel stopped.

[0243] Referring to FIG. 11, this figure illustrates an apparatus whichis essentially the same as that as shown in FIG. 6 so the same referencenumbers refer to the same elements. However, the apparatus additionallyincludes a defrost rotation component in the form of a second electricmotor 84 a, a shaft 85 a, the shaft 85 a engaging a pulley body 86 awhich also engages the belt 87; the apparatus also includes an electricswitch shown as a block element for energizing and de-energizing themotor 84 a; this second switch is likewise connectable to an electricalenergy source (shown in dotted outline) as is the previously mentionedswitch for motor 84. For this apparatus the motor 84 is configured so asto be able to urge rotation of the wheel 37 at a ventilation rotationspeed (e.g. 18 rpm); the motor 84 a on the other hand is configured soas to be able to urge rotation of wheel 37 at a defrost rotation speed(e.g 2 rpm, 1 rpm, etc). During a ventilation cycle the motor 84 isactivated while the motor 84 a is stopped or de-energized; during adefrost cycle the motor 84 a is active and the motor 84 is deactivated.The switches may if desired be separate switches but for ease of usethey may be embodied in a single switch configured such that in oneposition motor 84 is energized and motor 84 a is de-energized and inanother position the reverse occurs. Thus as may be appreciated theexploitation of such an apparatus entails the exploitation of thedefrost method of the present invention wherein the rotational speed ofthe wheel is reduced during a defrost cycle. It has been, for example,found that with an exterior temperature of −15° C. and a ventilationcycle time period of 32 minutes that a defrost rotation of 2 rpm or lessgives rises to a defrost time period of 8 minutes or less (i.e. at 2 rpmthe defrost time is 8 minutes).

[0244] The cabinet for an apparatus as described herein may also, ifdesired, include appropriate temperature sensor(s), air filters,electric wiring, control mechanisms for controlling the various motorsfor the ventilation and defrost cycles, etc. (none of which is shown inthe figures but which can be provided in any suitable or desiredconventional manner). These mechanism may example include programmablecomputer type controls. The controls may for example include a steppercontrol mechanism whereby the air flow rate may be passed from a highvalue, to a medium value, to a low value etc.; during these values theflow rate is intended to be more or less constant. The defrost cycle forexample may be normally be triggered by a thermistor or thermostatconnected to a timer. Referring to FIG. 6, the cabinet may for exampleinclude air filters 88 and 89 for filtering the fresh and exhaust airentering the cabinet 1; the filters are shown in dotted outline only.

[0245] The apparatus shown in FIG. 1 as mentioned above also includesmeans for balancing the flow of fresh and exhaust air therethrough.Before describing such balancing means, however, reference will first bemade to FIGS. 12 and 13 which illustrate the prior art system forbalancing the air flows through ventilator.

[0246] Turning to FIG. 12, the previously known ventilation systembalancing setup includes a ventilator apparatus 90. The exhaust airinflow into the ventilator 90 is shown by the arrow 91; the exhaust airoutflow out of the ventilator 90 is shown by the arrow 92; the fresh airinflow into the ventilator 90 is shown by the arrow 93; and the freshair outflow out of the ventilator 90 is shown by the arrow 94. Theductwork confining the exhaust air inflow includes a removeableflowmeter element 95 and an exhaust damper element 96. The ductworkconfining the fresh air outflow includes a removeable flowmeter element97 and an exhaust damper element 98. The elements 95 and 97 are knownairflow measuring devices. The damper elements 96 and 98 air known typesof circular plate dampers which are able to pivot about an axis so as tobe able at one extreme present themselves edgewise to the airflow so asto present minimum resistances to such airflow or at the other extremepresent the full face of their major surfaces perpendicularly to the airflow so as to present a maximum resistance to airflow.

[0247] Each of the elements 95 and 97 have a pair of pressure taps orconnector elements for respectively measuring the differential pressurein the exhaust air and fresh air ducts, namely, pressure tap elements100 and 101 for flowmeter element 95 and pressure tap elements 102 and103 for flowmeter element 97.

[0248] A differential pressure gauge 104 is shown in FIG. 13 which hastwo pressure tap connector tubes for being connected to suitablepressure taps such as mentioned above; a suitable gauge is theMagnehelic Differential pressure gauge (the word “Magnehelic” is aregistered Trademark) which may be obtained from Dwyer Instruments Inc.,Michigan City, Ind. U.S.A Two such gauges may be used for balancingpurposes; one being connected to the pressure taps 100 and 101 and theother being connected to the pressure taps 102 and 103 which may beconnected to a pair of pressure tap elements.

[0249] The exhaust and fresh air flows may be initially measured byplacing the balancing dampers 96 and 98 as seen parallel to the air flowin respective air ducts so as to present a minimum resistance to airflow. The fresh air and exhaust air flow rates may then be determinedusing the respective flow meters. The fresh air damper 98 may in then beadjusted by turning the damper manually using the pivot handle 105 so asincrease resistance to air flow in order to reduce the fresh air flowout of the ventilator to more or less equal the measured exhaust airinflow rate into the ventilator, i.e. as the damper is turned, so as topresent a larger surface area transverse to the direction of the airflow, the flowmeter connected to pressure taps 102 and 103 is monitoredand the adjustment of the damper 98 stopped once the flowmeter indicatesa flow rate more or less equal to that of the exhaust air flowing intothe ventilator as initially determined.

[0250] The exhaust air flow rate into the ventilator may then beremeasured and, if necessary, (i.e. if the exhaust flow is higher thanthe fresh air input flow), the exhaust air damper 96 may be adjustedusing the handle 106 (i.e. turned so as to provide a resistance to airflow) so as to reduce the exhaust air flow input into the ventilator tomore or less equal the adjusted fresh air flow out of the ventilator(e.g. the exhaust air flow may be adjusted so as to be somewhat smallerthan the fresh air flow so as to provide a slight overpressure in thebuilding, i.e. so as, for example, to inhibit uncontrolled entry offresh air through other parts of the building). Thereafter theflowmeters 95 and 97 are removed and replaced with appropriate ductportions. This procedure may take up to an hour or more of atechnician's.

[0251] The example apparatus of the present invention, as illustrated inthe FIGS. 1, 14, 15 and 16, includes two pairs of static pressure taps,namely taps 6 and 7 and taps 8 and 9. These pressure taps are defined bythe door 3 of the cabinet of the ventilation apparatus; the door 3 asmentioned above defines a wall of the fresh air and of the exhaust airpath means. The taps 6 and 7 are disposed on opposite sides of the wheelportion 37 a such that the fresh air stream path defined by the wheelportion 37 a is disposed therebetween. Similarly, the taps 8 and 9 aredisposed on opposite sides of the wheel portion 37 b such that the freshair stream path defined by the wheel portion 37 b is disposedtherebetween. These static pressure taps may of course be positioneddifferently then as shown; i.e. instead of being positioned on thecabinet door, they may be positioned on the top wall, side wall, etc. ofthe cabinet.

[0252] FIGS. 17 to 20 illustrate possible configurations for thepressure tap openings. For the tap openings shown, the mouths 107 and108 which are on the inside of cabinet are more or less flush with thewall surface defined by the foam element 4. The tap opening in FIGS. 1and 20 has a more or less uniform cross section over it's entire length;on the other hand the tap opening shown in FIG. 21 and 22 has a bevelledsurface 109 on the inside of the cabinet wall. The taps if desired mayinclude extensions projecting outwardly from the outer surface of thedoor to facilitate the connection of tubing thereto for connection to ameter.

[0253] As mentioned above pressure taps are disposed such that the freshair and exhaust air stream paths are between respective pressure taps.If, for example, however, an air filter 89 (see FIG. 6) is present ithas been found that the air filter 89 should also be disposed betweentaps 8 and 9 otherwise unreliable pressure readings were obtained; it isbelieved that this is due to turbulence induced by the filter whichinterferes with the possibility of obtaining a stable (static) pressurereading (such should be avoided for the reading).

[0254] Referring back to FIGS. 6, 7 and 8, the illustrated apparatus hasa first adjustable damper means which includes the above describeddamper element 22 and a second adjustable damper means which includesthe above described damper element 23. As mentioned above, although theillustrated ventilation apparatus is shown with these damper means theventilation apparatus need not if desired be provided with such dampermeans; the damper means may be separately provided, for example, by theduct work of the building to which the ventilation apparatus is to beattached.

[0255] As may be seen the first adjustable damper means is disposed onthe fresh air discharge side of the fresh air path means, and the secondadjustable damper means is disposed on the exhaust air intake side ofthe exhaust air path means. The first adjustable damper means includes ahandle 110 which is connected to the damper element 22 so that turningthe handle will cause the damper element 22 to pivot about its pivotaxis and block or unblock the air flow path. Similarly, the secondadjustable damper means includes a handle 111 which is connected to thedamper element 23 so that turning the handle will cause the damperelement 23 to pivot about its pivot axis and block or unblock the airflow path.

[0256] In order to be able to exploit the balancing means provided withthe ventilation apparatus a calibration airflow chart must bepredetermined for each of the fresh air and exhaust air sides of theapparatus; the calibration chart will relate pressure difference valuesacross each of the pressure tap pairs to a particular air flow ratevalue.

[0257] Referring to FIG. 21, this figure shows an apparatus asillustrated in the above described FIGS. 1 to 10; the dampers 22 and 23being removed. The ventilation apparatus is attached to ducting whichincludes: four static pressure measuring meter elements 113 a, 113 b,113 c and 113 d; four pressure difference meters 114; two venturi typeairflow measuring devices indicated generally by the reference numerals115 and 116; and four dampers 116 a, 116 b, 116 c and 116 d. Airflow isinduced through each of the fresh air and exhaust air sides of theapparatus by the motor of the apparatus itself. The air flow rate isvaried by manipulating the dampers 116 a to 116 d. Thus the blower motoris started and the dampers 116 a to 116 d are manipulated until eachrespective meters 113 a to 113 d measures 0.1 inches of water absolute;the air flow rates are determined by the venturi assembly and the staticpressure difference noted for such inflow and outflow rates across thepairs of static taps. This procedure is repeated at increments of 0.05inches of water absolute (i.e. at 0.15 inches, 0.2 inches, 0.25 inchesand so on until the flow rate is essentially zero cfm) at the meters 116a to 116 d; the purpose of increasing the static air pressure is toreduce the air flow. For each effective air flow rate a pressuredifference reading is thus recorded so as to establish for example acalibration columnar chart for each pressure tap pair, the chart havingfor example one column for airflow (e.g. cubic feet per minute—cfm) anda column for the pressure differences (e.g. inches of water)corresponding to each of the airflow rates; please see the abovementioned charts I and II.

[0258] Alternatively, rather than manipulating the dampers 116 a to 116d, the air flow rate may be varied by connecting the motor to a variablespeed controller such as for example a Variac or if desired differentblower motors having different fixed speeds may substituted one afterthe other in the apparatus.

[0259] Although each ventilator apparatus may be provided with anindividual calibration chart this may not be economically practical.Thus, a single chart may be used with a plurality of ventilators havingthe same structural features; the chart having been obtained bycalibrating a statistically acceptable number of machines so as toobtain a practical average value chart.

[0260] It is to be noted that the statistically obtained calibrationchart can only be used for ventilation apparatuses which are of the sameconstruction. Different calibration charts are to be expected if forexample the exchanger core is different form one ventilator to the next.

[0261] An apparatus as described herein may be configured as a more orless constant flow apparatus wherein flow rates may be adjusted betweenhigh, medium and low rates; i.e. the blower wheel has high, medium andlow rotation speed settings. Referring to FIG. 22, an apparatusconnected to the ductwork of a building may, for example, be balancedfor example at a high (blower) speed level by initially measuring thefresh air pressure difference across the fresh air pressure tap pair(i.e. taps 6 and 7) and the exhaust air pressure difference across theexhaust air pressure tap pair (i.e. taps 8 and 9); the balancing dampers110 and 111 being parallel to the air flow so as to present a minimumresistance to air flow. The fresh air and exhaust air pressuredifferences may then be determined using the respective pressuredifference meters 114. The air flow rate values corresponding to themeasured static pressure differences will then be determined byreferring to the above mentioned respective calibration charts. Thefresh air damper 110 may if necessary be adjusted so as to reduce thefresh air flow out of the ventilator to more or less equal the exhaustair input to the ventilator, i.e. as the fresh air damper is turned, soas to present a larger surface area transverse to the direction of theair flow, the appropriate pressure difference meter is monitored and theadjustment stopped once the pressure difference meter indicates apressure difference indicative of an air flow rate more or less equal tothat of the exhaust air flowing into the ventilator as initiallydetermined.

[0262] The pressure difference (across taps 8 and 9) for the exhaust airinto the ventilator may then be remeasured and the calibration chartsreconsulted; if necessary, (i.e. if the exhaust flow is higher than thefresh air input flow), the exhaust air damper may be adjusted (i.e.turned into the air flow) so as to change the pressure difference acrosstaps 8 and 9 so as to reflect a reduced exhaust air flow input into theventilator which is more or less equal to the adjusted fresh air flowout of the ventilator (e.g. the exhaust air flow may be adjusted so asto be somewhat smaller than the fresh air flow so as to provide a slightoverpressure in the building, i.e. so as, for example, to inhibituncontrolled entry of fresh air through other parts of the building).This procedure may take up for example about 15 minutes of atechnician's time.

[0263] Although as mentioned above the ventilator may be balanced at ahigh blower speed level the balancing procedure does not have to berepeated for the other blower speed levels.

[0264] Although the air flow balancing aspect of the present inventionhas been particularly described above with respect to a ventilatorprovided with a rotary exchanger wheel, this aspect may equally beapplied to ventilators having other types of exchanger means. Theexchanger means may, for example, take the form of a stationary cubediscussed above. Thus, FIG. 23 schematically shows by way of additionalexample a ventilator such as described in the above mentioned U.S. Pat.No. 5,193,610 provided with a cubic stationary exchanger core 120 andalso with static pressures taps 6 a, 7 a, 8 a, and 9 a; the pressuretaps are constructed in a manner analogous to that for taps 6, 7, 8 and9 mentioned above. As may be seen the fresh air flow path 26 a and theexhaust air flow path 27 a crisscross each other through the exchangercore 120. The fresh air pressure difference is taken across taps 6 a and7 a; the exhaust air pressure difference is taken across taps 8 a and 9a. As in the case for a ventilator as shown in FIGS. 1 to 10,calibration charts must be obtained for this ventilator type in a manneras described with respect to FIG. 21. Thereafter, the balancing of theventilator connected to the duct work of a building proceeds asdescribed above.

[0265] Turning now to FIGS. 24 and 25, these figures illustrate afurther embodiment of a ventilation apparatus in accordance with thepresent invention, namely, a ventilation apparatus which comprises adesiccant type wheel and a sensible heat exchanger (i.e. a non-rotatingsensible heat exchanger). This type of apparatus exploits the method ofthe present invention whereby exhaust air is first dried (and cooled tosome extent) and then further just cooled by a sensible heat exchanger.

[0266]FIG. 24 shows a schematic illustration of a pre-drying typeventilation apparatus in accordance with the present invention. Theapparatus is generally provided with a desiccant rotary wheel 130, ablower assembly 131 and a sensible cube shaped exchanger 132 such asdescribed in the above mentioned U.S. Pat. No. 5,193,610. The exchanger132 is provided with a group of parallel channels disposed at rightangles to another group of parallel channels as described in the abovepatent. One group of the channels is used to define a first air streampath 133 and the other a fourth air stream path 134. The wheel 130similarly defines a second air stream path 135 and a third air streampath 136. As may be seen the path of incoming fresh air is identified bythe arrows 137 and the outgoing exhaust air is identified by the arrows138. Thus as may be seen warm humid exhaust air enters third air streampath 136 where it loses moisture and some heat; the dried exhaust airthen travels through the fourth air stream path 134 giving up additionalheat to the fresh air in the first air stream path 133. The warmed freshair then passes through the second air stream path 135 where it may pickup water moisture and some additional sensible heat before being passedout of the apparatus for delivery to a building. In this manner,relatively humid exhaust air is not immediately subjected to an exchangewith ambient exterior air which is relatively cool (e.g. −20° C.), butto an exchange with air which has been pre-heated to a highertemperature; this may extend the time during which the desiccant wheelis not iced up. Since the exhaust air sent on to the sensible exchangerfrom the desiccant exchanger carries less water there is also theadvantage that the sensible exchanger will also not experience an iceblockage sufficient to require de-icing for a relatively extended periodof time as compared to the use of such a wheel or stationary core alone.It has been found, for example, that a system set up as in FIG. 1 to 8may require defrosting after about 32 minutes at an exterior airtemperature of −15° C. or lower whereas a system set up generally as inFIG. 24 may go for up to 6 hours or more without the need to bedefrosted; this represents a considerable energy efficiency gain.

[0267] A pre-dry apparatus as described herein and in particular withrespect to FIG. 24 need not if so desired but may include some sort ofdefrost means. The defrost means may, for example, be as described abovenamely a defrost rotation component or a defrost air by-pass means. Thedefrost mechanism may, however, merely comprise the re-routing of theexhaust air through the fresh air side of the exchanger units back tothe building. The blower assembly need not be disposed between theexchangers as in FIG. 24 but to one side thereof as shown in FIG. 25.

[0268] Thus for example FIG. 25 illustrates an example pre-dryventilation system of the present invention which provides for a defrostfunction by the above mentioned exhaust air re-routing. The apparatus asshown comprises the elements as shown in FIG. 8 and to the extent thatan element is common the same reference numerals are used in FIG. 24.The illustrated apparatus does not, however, have a defrost rotationcomponent, i.e. it does not have an electrical switch whereby the motorused for urging the wheel 37 to rotate may be turned off during thedefrost cycle.

[0269] As mentioned many of the components of the apparatus shown inFIG. 25 are common to the apparatus as shown in FIG. 8. Accordingly, thedescription of the common elements may be had by reference back to theabove description relating to FIG. 8 and the related figures. Theessential difference between the apparatus of FIG. 8 and FIG. 25 is thatthe apparatus in FIG. 25 is configured to include a rectangular(non-rotating) sensible heat exchanger 140 as described in thepreviously mention U.S. Pat. No. 5,193,610. The exchanger 140 is held inplace as described in this patent such that the diagonally disposedchannels are inclined such that when the apparatus is horizontallydisposed these channels are self draining due to gravity, i.e. any waterliquid therein flows downwardly out of the core. In the figure one ofeach of these diagonally disposed channels is designated by a referencenumeral, namely reference numeral 141 and 142 respectively; thesechannels will be referred to hereinafter using these reference numerals.The channels are defined by air-to-air heat exchange walls.

[0270] The channels 141 define a first air stream path; the channels 142define a fourth air stream path. These paths criss-cross each other.

[0271] The part 37 a of the wheel 37 may be considered as defining athird air stream path and the part 37 b a second air stream path. Thesepaths are parallel to each other. As in the case of FIG. 8, theapparatus shown in FIG. 25 is in a ventilation configuration. The freshair and exhaust air paths are mapped out by the arrows 26 and 27respectively. As may be seen, during the ventilation cycle the fresh airtravels first through the first air path defined by the channels 141 andthen passes through the second air path defined by the part 37 b ofwheel 37. The exhaust air on the other hand flows through the third airstream path defined by the part 37 a of the wheel and then flows throughthe channels 142 which define the forth air stream path.

[0272] If the apparatus in FIG. 25 is to be defrosted it is placed in adefrost configuration by the lowering of the damper member 43 into thepreviously mentioned short channel member so as to block this channeland allow the exhaust air to be re-routed upwardly into the upper partof the cabinet from whence it flows back to the building first throughthe channels 141 and then the part 37 b of the wheel 37 and in so doingmay effect a defrosting of the apparatus due to recirculation of theexhaust air.

[0273] Although the apparatus as shown in FIG. 25 does not have adefrost rotation component, it may if so desired be suitably modified tohave, for example, a rotation attenuation means as shown in FIG. 8 or inFIG. 11.

[0274] Although the example apparatus shown in FIGS. 24 and 25 exploitsa cubic non-rotating sensible heat exchanger it is of course to beunderstood that the cubic exchanger may be replaced by a sensible heatrotary wheel exchanger having the configuration of wheel 37 in FIGS. 1to 8 and being urged into rotation during ventilation by the same sortof motor/pulley/belt means. The use of a further wheel would mean thatthe fresh air and exhaust air paths would not criss-cross each otherduring operation of the apparatus. If desired defrost means as describedabove may be incorporated into such a ventilation device.

[0275] Turning now to FIGS. 26 and 27 these illustrate in schematicfashion a defrostable ventilation apparatus which has a by-pass meanswhereby exhaust air may be returned to the building using the fresh airdischarge side of an apparatus, i.e. a by-pass channel is used to routeexhaust air past the fresh air stream part of an exchanger wheel so asto avoid having the wheel pass heat back to the exhaust defrost air. Forthese figures the same reference numerals are used for the elementscommon with those of the apparatus of FIGS. 1 to 10. Basically theapparatus a further partition member 150. The apparatus still has thedamper member 43 and attendant means for the displacement thereof foropening and closing opening 32. When the damper member 43 is in adefrost configuration such that the opening 32 is open, the exhaust airis expelled into the pocket partially defined by the partition member150, the partition member 25 and the other wall members disposedthereabout; the top wall is shown for purposes of illustration as beingremoved in both FIGS. 26 and 27. The exhaust air would then be able totravel through the opening 151 of tube member 152 and exit opening 153into the fresh air discharge side of the apparatus. For the ventilationconfiguration the damper, member 43 would be raised to close the opening32 and air would circulate as described above. Referring to FIG. 27 thewall portion 155 of the partition member 150 has a small opening 156 toallow motion of the member 61 to manipulate the damper 42. The portionof the partition member 150 apart from the wall member 155 is defined bythe wall of the housing 150 and by a wall extension projectingdownwardly from the housing 50 to the partition member 25 below.Although the by-pass channel in the illustrated apparatus has an exitcommunicating with the discharge side of the fresh air outlet side, theby-pass channel may if desired be defined by a separate channel memberhaving its own separate discharge outlet for the air.

[0276] It is to be understood that the apparatus of the presentinvention may take many other forms without departing from the spiritand scope thereof as described in the present specification; thespecific embodiment illustrated above being provided by way ofillustrative example only.

What is claimed:
 1. A defrostable ventilation apparatus, for exchangingair between the interior and exterior of a building, for transferringwater moisture and sensible heat between exhaust air taken from thebuilding and fresh air taken from the exterior ambient air for deliveryto the building, and wherein air from the interior of the building isused as defrost air to defrost the ventilation apparatus, saidventilation apparatus having fresh air path means having a fresh airintake side and a fresh air discharge side, exhaust air path meanshaving an exhaust air intake side and an exhaust air discharge side, arotary exchanger wheel for transfer of water moisture and sensible heatbetween said exhaust air and said fresh air, said exchanger wheel beingconfigured and rotatably disposed so as to define a first air streampath and a second air stream path, said first air stream path defining aportion of said fresh air path means between the fresh air intake sideand the fresh air discharge side thereof and said second air stream pathdefining a portion of said exhaust air path means between the exhaustair intake side and the exhaust air discharge side thereof, and aventilation rotation component for inducing, during a ventilation cycle,ventilation rotation of said exchanger wheel through said fresh air pathmeans and said exhaust air path means, characterized in that saidapparatus comprises defrost air path means for conveying defrost air tosaid fresh air intake side, said defrost air path means being configuredto connect the exhaust air discharge side with the fresh air intake sidefor conveying defrost air to said fresh air intake side from saidexhaust air discharge side, a damper component, said damper componentbeing displaceable between a ventilation configuration for a ventilationcycle wherein said defrost air path means is closed off and said freshair intake side and exhaust air discharge side are open, and a defrostconfiguration for a defrost cycle wherein said fresh air intake side andsaid exhaust air discharge side are closed off and said defrost air pathmeans is open, and a defrost rotation component for inducing, during adefrost cycle, said rotary exchanger wheel to rotate at a defrostrotation speed of from 0 to 2 rpm through said fresh air path means andsaid exhaust air path means, and wherein during a ventilation cycle,when said damper component is in said ventilation configuration, freshair is able to flow through said fresh air path means and exhaust air isable to flow through said exhaust air path means, and during a defrostcycle, when said damper component is in said defrost configuration,defrost air taken from the building, is able to circulate, for deliveryback into the building, through said exhaust air intake side, throughsaid second air stream path, then through said defrost air path means,through said first air stream path, and through said fresh air dischargeside.
 2. A ventilation apparatus as defined in claim 1 wherein saidfresh air path means includes a fan for moving fresh air through saidfresh air path means and said exhaust air means includes a fan formoving exhaust air through said exhaust air path means.
 3. A ventilationapparatus as defined in claim 1 wherein said damper component comprisesa first damper component and a second damper component, said firstdamper component being displaceable between a ventilation configurationwherein said defrost air path means is closed off and said fresh airintake side is open and a defrost configuration wherein said defrost airpath means is open and said fresh air intake side is closed off and saidsecond damper component being displaceable between a ventilationconfiguration wherein said exhaust air discharge side is open and adefrost configuration wherein said exhaust air discharge side is closedoff, and wherein during a ventilation cycle, when said first and seconddamper components are in said respective ventilation configurations,fresh air is able to flow through said fresh air path means and exhaustair is able to flow through said exhaust air path means, and during adefrost cycle, when said first and second damper components are in saidrespective defrost configurations, defrost air taken from the building,is able to circulate, for delivery back into the building, through saidexhaust air intake side, through said second air stream path, thenthrough said defrost air path means, through said first air stream path,and through said fresh air discharge side.
 4. The ventilation apparatusas defined in claim 3 wherein said fresh air path means, said exhaustair path means, said rotary exchanger wheel, and said defrost air pathmeans, are disposed in a cabinet, wherein said fresh air intake side,said exhaust air discharge side, said fresh air discharge side and saidexhaust air intake side each includes one respective air opening in anouter wall of said cabinet, wherein a partition wall in said cabinetseparates said exhaust air discharge side from said fresh air intakeside, and wherein said defrost air path means comprises an opening insaid partition wall.
 5. A ventilation apparatus as defined in claim 4wherein said apparatus includes a fan component mounted in said cabinetfor moving fresh air through said fresh air path means and for movingexhaust air through said exhaust air path means, said fan componentcomprising one electric motor and two blower wheels operativelyconnected thereto, said fresh air path means including one said blowerwheel and said exhaust path means including the other said blower wheel.6. A defrostable ventilation apparatus, for exchanging air between theinterior and exterior of a building, for transferring water moisture andsensible heat between exhaust air taken from the building and fresh airtaken from the exterior ambient air for delivery to the building, andwherein air from the interior of the building is used as defrost air todefrost the ventilation apparatus, said ventilation apparatus havingfresh air path means having a fresh air intake side and a fresh airdischarge side, exhaust air path means having an exhaust air intake sideand an exhaust air discharge side, a rotary exchanger wheel for transferof water moisture and sensible heat between said exhaust air and saidfresh air, said exchanger wheel being configured and rotatably disposedso as to define a first air stream path and a second air stream path,said first air stream path defining a portion of said fresh air pathmeans between the fresh air intake side and the fresh air discharge sidethereof and said second air stream path defining a portion of saidexhaust air path means between the exhaust air intake side and theexhaust air discharge side thereof, and a ventilation rotation componentfor inducing, during a ventilation cycle, ventilation rotation of saidexchanger wheel through said fresh air path means and said exhaust airpath means, characterized in that said apparatus comprises defrost airpath means for conveying defrost air to said fresh air intake side, saiddefrost air path means being configured to connect the exhaust airdischarge side with the fresh air intake side for conveying defrost airto said fresh air intake side from said exhaust air discharge side, anda damper component, said damper component being displaceable between aventilation configuration for a ventilation cycle wherein said defrostair path means is closed off and said fresh air intake side and exhaustair discharge side are open, and a defrost configuration for a defrostcycle wherein said fresh air intake side and said exhaust air dischargeside are closed off, and said defrost air path means is open, acomponent for stopping, during a defrost cycle, said rotary exchangerwheel from rotating, and wherein during a ventilation cycle, when saiddamper means is in said ventilation configuration, fresh air is able toflow through said fresh air path means and exhaust air is able to flowthrough said exhaust air path means, and during a defrost cycle, whensaid damper means is in said defrost configuration, defrost air takenfrom the building, is able to circulate, for delivery back into thebuilding, through said exhaust air intake side, through said second airstream path, then through said defrost air path means, through saidfirst air stream path, and through said fresh air discharge side.
 7. Aventilation apparatus as defined in claim 6 wherein said ventilationrotation component comprises an electric motor and said component forstopping the rotation of said exchanger wheel comprises an electricswitch configured so as to be able to de-energize said motor during adefrost cycle.
 8. A ventilation apparatus as defined in claim 6 whereinsaid fresh air path means includes a fan for moving fresh air throughsaid fresh air path means and said exhaust air means includes a fan formoving exhaust air through said exhaust air path means.
 9. A ventilationapparatus as defined in claim 6 wherein said damper component comprisesa first damper component and a second damper component, said firstdamper component being displaceable between a ventilation configurationwherein said defrost air path means is closed off and said fresh airintake side is open and a defrost configuration wherein said defrost airpath means is open and said fresh air intake side is closed off and saidsecond damper component being displaceable between a ventilationconfiguration wherein said exhaust air discharge side is open and adefrost configuration wherein said exhaust air discharge side is closedoff, and wherein during a ventilation cycle, when said first and seconddamper components are in said respective ventilation configurations,fresh air is able to flow through said fresh air path means and exhaustis able to flow through said exhaust air path means, and during adefrost cycle, when said first and second damper components are in saidrespective defrost configurations, defrost air taken from the building,is able to circulate, for delivery back into the building, through saidexhaust air intake side, through said second air stream path, thenthrough said defrost air path means, through said first air stream path,and through said fresh air discharge side,.
 10. The ventilationapparatus as defined in claim 9 wherein said fresh air path means, saidexhaust air path means, said rotary exchanger wheel, and said defrostair path means, are disposed in a cabinet, wherein said fresh air intakeside, said exhaust air discharge side, said fresh air discharge side andsaid exhaust air intake side each includes one respective air opening inan outer wall of said cabinet, wherein a partition wall in said cabinetseparates said exhaust air discharge side from said fresh air intakeside, and wherein said defrost air path means comprises an opening insaid partition wall.
 11. A ventilation apparatus as defined in claim 10wherein said apparatus includes a fan component mounted in said cabinetfor moving fresh air through said fresh air path means and for movingexhaust air through said exhaust air path means, said fan componentcomprising one motor and two blower wheels operatively connectedthereto, said fresh air path means including one said blower wheel andsaid exhaust path means including the other said blower wheel.
 12. Amethod for defrosting a ventilation apparatus configured to transferwater moisture and sensible heat between fresh air delivered to andexhaust air taken from a building by means of a rotating exchanger wheeldefining a first air path for fresh air and a second air path forexhaust air, said method comprising i) directing exhaust air to flowthrough one of said first and second air paths and then through theother of said first and second air paths back into said building, andii) inducing the rotary exchanger wheel to rotate at a rotational speedof from 0 to 2 rpm such that said rotary exchanger wheel is able to bedefrosted by said exhaust air.
 13. A method for defrosting a ventilationapparatus configured to transfer water moisture and sensible heatbetween fresh air delivered to and exhaust air taken from a building bymeans of a rotating exchanger wheel defining a first air path for freshair and a second air path for exhaust air, said method comprising i)directing exhaust air to flow through said second air path and thenthrough said first air path back into said building, and ii) stoppingthe rotation of said exchanger wheel such that said rotary exchangerwheel is able to be defrosted by said exhaust air.
 14. A defrostableventilation apparatus, for exchanging air between the interior andexterior of a building, for transferring water moisture and sensibleheat between exhaust air taken from the building and fresh air takenfrom the exterior ambient air for delivery to the building, and whereinair from the interior of the building is used as defrost air to defrostthe ventilation apparatus, said ventilation apparatus having fresh airpath means having a fresh air intake side and a fresh air dischargeside, exhaust air path means having an exhaust air intake side and anexhaust air discharge side, a rotary exchanger wheel for transfer ofwater moisture and sensible heat between said exhaust air and said freshair, said exchanger wheel being configured and rotatably disposed so asto define a first air stream path and a second air stream path, saidfirst air stream path defining a portion of said fresh air path meansbetween the fresh air intake side and the fresh air discharge sidethereof and said second air stream path defining a portion of saidexhaust air path means between the exhaust air intake side and theexhaust air discharge side thereof, and a rotation component forinducing rotation of said exchanger wheel through said fresh air pathmeans and said exhaust air path means, characterized in that saidapparatus comprises defrost air path means for providing an air pathby-passing said first air steam path, said defrost air path meanscomprising a defrost air discharge side and being configured to connectthe exhaust air discharge side with the defrost air discharge sidethereof for conveying defrost air to said defrost air discharge sidefrom said exhaust air discharge side, and a damper component, saiddamper component being displaceable between a ventilation configurationfor a ventilation cycle wherein said defrost air path means is closedoff and said fresh air intake side and said exhaust air discharge sideare open, and a defrost configuration for a defrost cycle wherein saidfresh air intake side and said exhaust air discharge side are closed offand said defrost air path means is open, and wherein during aventilation cycle, when said damper component is in said ventilationconfiguration, fresh air is able to flow through said fresh air pathmeans and exhaust air is able to flow through said exhaust air pathmeans, and during a defrost cycle, when said damper component is in saiddefrost configuration, defrost air taken from the building, is able tocirculate, for delivery back into the building, through said exhaust airintake side, through said second air stream path, then through saiddefrost air path means, and through said defrost air discharge side. 15.A defrostable ventilation apparatus, for exchanging air between theinterior and exterior of a building, for transferring water moisture andsensible heat between exhaust air taken from the building and fresh airtaken from the exterior ambient air for delivery to the building, andwherein air from the interior of the building is used as defrost air todefrost the ventilation apparatus, said ventilation apparatus havingfresh air path means having a fresh air intake side and a fresh airdischarge side, exhaust air path means having an exhaust air intake sideand an exhaust air discharge side, a rotary exchanger wheel for transferof water moisture and sensible heat between said exhaust air and saidfresh air, said exchanger wheel being configured and rotatably disposedso as to define a first air stream path and a second air stream path,said first air stream path defining a portion of said fresh air pathmeans between the fresh air intake side and the fresh air discharge sidethereof and said second air stream path defining a portion of saidexhaust air path means between the exhaust air intake side and theexhaust air discharge side thereof, and a rotation component forinducing rotation of said exchanger wheel through said fresh air pathmeans and said exhaust air path means, characterized in that saidapparatus comprises defrost air path means for providing an air pathby-passing said first air steam path, said defrost air path means beingconfigured to connect the exhaust air discharge side with the fresh airdischarge side for conveying defrost air to said fresh air dischargeside from said exhaust air discharge side, and a damper component, saiddamper component being displaceable between a ventilation configurationfor a ventilation cycle wherein said defrost air path means is closedoff and said fresh air intake side and exhaust air discharge side areopen, and a defrost configuration for a defrost cycle wherein said freshair intake side and said exhaust air discharge side are closed off, andsaid defrost air path means is open, and wherein during a ventilationcycle, when said damper component is in said ventilation configuration,fresh air is able to flow through said fresh air path means and exhaustair is able to flow through said exhaust air path means, and during adefrost cycle, when said damper component is in said defrostconfiguration, defrost air taken from the building, is able tocirculate, for delivery back into the building, through said exhaust airintake side, through said second air stream path, then through saiddefrost air path means, and through said fresh air discharge side.
 16. Aventilation apparatus, for exchanging air between the interior andexterior of a building, and for transferring, a member of the groupcomprising i) sensible heat and ii) sensible heat and water moisture,between exhaust air taken from the building and fresh air taken from theexterior ambient air for delivery to the building, said ventilationapparatus comprising fresh air path means having a fresh air intake sideand a fresh air discharge side, exhaust air path means having an exhaustair intake side and an exhaust air discharge side, an exchanger forexchanging, a member selected from the group comprising i) sensible heatand ii) sensible heat and water moisture, between fresh air and exhaustair, said exchanger means being configured and disposed so as to definea first air stream path and a second air stream path, said first airstream path defining a portion of the fresh air path means between thefresh air intake side and the fresh air discharge side thereof and saidsecond air stream path defining a portion of said exhaust air path meansbetween the exhaust air intake side and the exhaust air discharge sidethereof, characterized in that said ventilation apparatus comprisesfirst, second, third and fourth static pressure taps, said first andsecond static pressure taps being configured and disposed for thedetermination of a first static pressure difference therebetween in saidfresh air path means, said first air stream path being disposed betweensaid first and second static pressure taps, said third and fourth staticpressure taps being configured and disposed for the determination of asecond static pressure difference therebetween in said exhaust air pathmeans, said second air stream path being disposed between said third andfourth static pressure taps.
 17. A ventilation apparatus as defined inclaim 16 wherein said apparatus comprises a first adjustable dampercomponent for adjusting air flow through said fresh air path means, anda second adjustable damper component for adjusting air flow through saidexhaust air path means.
 18. A ventilation apparatus as defined in claim17 wherein said first adjustable damper component is disposed on thefresh air discharge side of said fresh air path means, and said secondadjustable damper component is disposed on the exhaust air intake sideof said exhaust air path means.
 19. A ventilation apparatus as definedin claim 16 wherein said first and second pressure taps each comprise apressure sampling aperture defined by a wall of said fresh air pathmeans and wherein said third and fourth pressure taps each comprise apressure sampling apertures defined by a wall of said exhaust air pathmeans.
 20. A ventilation apparatus as defined in claim 16 wherein saidapparatus includes a fan component for forcing air to pass through saidfirst and second air stream paths.
 21. A ventilation apparatus asdefined in claim 16 wherein said ventilation apparatus is configured asa constant flow ventilation apparatus.
 22. A ventilation apparatus asdefined in claim 16 wherein said exchanger comprises a rotary exchangerwheel for exchanging sensible heat.
 23. A ventilation apparatus asdefined in claim 16 wherein said exchanger comprises a rotary exchangerwheel for exchanging sensible heat and water moisture.
 24. A ventilationapparatus as defined in claim 16 wherein said exchanger elementcomprises a sensible heat exchanger and comprises air-to-air heatexchanging walls between said first and second air stream paths.
 25. Aventilation apparatus as defined in claim 24 wherein said sensible beatexchanger is of a rectangular parallelepiped shape, the first and secondair paths thereof are disposed at right angles to each other and saidsensible heat exchanger element is so disposed such that the first andsecond air paths are diagonally oriented so that they are self draining.26. A ventilation apparatus as defined in claim 16 wherein said freshair path means, said exhaust air path means, and said heat exchangermeans are disposed in a cabinet, wherein said fresh air intake side,said exhaust air discharge side, said fresh air discharge side and saidexhaust air intake side each includes one respective air opening in awall of said cabinet, wherein said first and second pressure tap meanseach comprise a pressure sampling aperture defined by a wall of saidfresh air path means and wherein said third and fourth pressure tapmeans each comprise a pressure sampling apertures defined by a wall ofsaid exhaust air path means.
 27. A ventilation apparatus as defined inclaim 26 wherein said fresh air path means comprises a wall of saidcabinet which defines said apertures of said first and second pressuretap means, wherein said exhaust air path means comprises a wall of saidcabinet which defines said apertures of said third and fourth pressuretap means.
 28. A ventilation apparatus as defined in claim 27 whereinsaid apparatus comprises a first adjustable damper component foradjusting air flow through said fresh air path means, and a secondadjustable damper component for adjusting air flow through said exhaustair path means.
 29. A ventilation apparatus as defined in claim 28wherein said first adjustable damper component is disposed on the freshair discharge side of said fresh air path means, and said secondadjustable damper component is disposed on the exhaust air intake sideof said exhaust air path means.
 30. A ventilation apparatus as definedin claim 29 wherein said exchanger means comprises a rotary exchangerwheel.
 31. A ventilation apparatus as defined in claim 30 wherein saidapparatus includes a fan component for forcing air to pass through saidfirst and second air stream paths.
 32. A method for balancing fresh airand exhaust air flow through an operating ventilation apparatus, saidventilation apparatus being configured for exchanging air between theinterior and exterior of a building and for transferring, a member ofthe group comprising i) sensible heat and ii) sensible heat and watermoisture, between exhaust air taken from the building and fresh airtaken from the exterior ambient air for delivery to the building, saidventilation apparatus comprising fresh air path means having a fresh airintake side and a fresh air discharge side, exhaust air path meanshaving an exhaust air intake side and an exhaust air discharge side, anexchanger for exchanging, a member selected from the group comprising i)sensible heat and ii) sensible heat and water moisture, between freshair and exhaust air, said exchanger means being configured and disposedso as to define a first air stream path and a second air stream path,said first air stream path defining a portion of the fresh air pathmeans between the fresh air intake side and the fresh air discharge sidethereof and said second air stream path defining a portion of saidexhaust air path means between the exhaust air intake side and theexhaust air discharge side thereof, said method comprising determining afirst static pressure difference in said fresh air path means, saidfirst static pressure difference being determined with respect to firstand second static pressure sampling locations, said first air streampath being disposed between said first and second static pressuresampling locations, determining a second static pressure difference insaid exhaust air path means, said second static pressure differencebeing determined with respect to third and fourth static pressuresampling locations, said second air stream path being disposed betweensaid third and fourth static pressure sampling locations, comparingpredetermined air flow values represented by each of said so obtainedfirst and second static pressure differences so as to determine if saidpredetermined fresh air and exhaust air flow values are at leastsubstantially the same.
 33. A method as defined in claim 32, whereinsaid apparatus includes a first adjustable damper component foradjusting air flow through said fresh air path means, and a secondadjustable damper component for adjusting air flow through said exhaustair path means.
 34. A method as defined in claim 33, said methodincluding manipulating at least one of said first and second dampercomponents until said so obtained first and second static pressuredifferences are each set at a value whereby each static pressuredifference represents a respective predetermined air flow value which isat least substantially the same as the other.
 35. A ventilationapparatus, for exchanging air between the interior and exterior of abuilding, and for transferring water moisture and sensible heat betweenexhaust air taken from the building and fresh air taken from theexterior ambient air for delivery to the building, said ventilationapparatus comprising fresh air path means having a fresh air intake sideand a fresh air discharge side, exhaust air path means having an exhaustair intake side and an exhaust air discharge side, an exchangercomprising a desiccant exchanger element for transfer of water moistureand sensible heat between said exhaust air and said fresh air, and asensible heat exchanger element for transfer of sensible heat betweensaid exhaust air and said fresh air, said desiccant exchanger elementcomprising a rotary exchanger wheel configured and rotatably disposed soas to define a second air stream path and a third air stream path, saidsecond air stream path defining a portion of said fresh air path meansand said third air stream path defining a portion of said exhaust airpath means, said sensible heat exchanger element comprising a first airpath defining a portion of said fresh air path means and a fourth airpath defining a portion of said exhaust air path means, said fresh airpath means and said exhaust air path means being disposed and configuredsuch that during a ventilation cycle, exhaust air entering the exhaustair intake side flows through said third air stream path and thenthrough said fourth air stream path and fresh entering said the freshair intake side flows through said first air stream path and thenthrough said second air stream path, said ventilation apparatusincluding a rotation component for inducing rotation of said exchangerwheel through said fresh air path means and said exhaust air path means.36. A ventilation apparatus as defined in claim 35 wherein said sensibleheat exchanger element comprises air-to-air heat exchanging wallsbetween said first and fourth air paths.
 37. A ventilation apparatus asdefined in claim 36 wherein said sensible heat exchanger element is of arectangular parallelepiped shape, the first and fourth air paths thereofare disposed at right angles to each other and said sensible heatexchanger element is so disposed such that the first and fourth airpaths are diagonally oriented so that they are self draining.
 38. Aventilation apparatus as defined in claim 35 wherein said sensible heatexchanger element is a rotary sensible heat exchanger wheel configuredand rotatably disposed so as to define said first and fourth air streampaths and said apparatus includes a rotation component for inducingrotation of said sensible heat exchanger wheel through said fresh airpath means and said exhaust air path means.
 39. A method for exchangingair between the interior and exterior of a building, and fortransferring water moisture and sensible heat between exhaust air takenfrom the building and fresh air taken from the exterior ambient air fordelivery to the building, said method comprising removing water moisturefrom exhaust air so as to obtain dried exhaust air, transferringsensible heat from said dried exhaust air to fresh air taken from theexterior ambient air so as to obtain warmed fresh air and cooled exhaustair, exhausting said cooled exhaust air to the exterior ambient airtransferring water moisture removed from said exhaust air to said warmedfresh air so as to obtain humidified warmed fresh air and deliveringsaid humidified warmed fresh air to the interior of said building.
 40. Adefrostable ventilation apparatus, for exchanging air between theinterior and exterior of a building, for transferring water moisture andsensible heat between exhaust air taken from the building and fresh airtaken from the exterior ambient air for delivery to the building, andwherein air from the interior of the building is used as defrost air todefrost the ventilation apparatus, said ventilation apparatus comprisingfresh air path means having a fresh air intake side and a fresh airdischarge side, exhaust air path means having an exhaust air intake sideand an exhaust air discharge side, an exchanger comprising a desiccantexchanger element for transfer of water moisture and sensible heatbetween said exhaust air and said fresh air, and a sensible heatexchanger element for transfer of sensible heat between said exhaust airand said fresh air, said desiccant exchanger element comprising a rotaryexchanger wheel configured and rotatably disposed so as to define asecond air stream path and a third air stream path, said second airstream path defining a portion of said fresh air path means and saidthird air stream path defining a portion of said exhaust air path means,said sensible heat exchanger element comprising a first air pathdefining a portion of said fresh air path means and a fourth air pathdefining a portion of said exhaust air path means, said first and secondair stream paths defining respective portions of said fresh air pathmeans between the intake and discharge sides of said fresh air pathmeans, said third and fourth air stream paths defining respectiveportions of said exhaust air path means between the intake and dischargesides of said exhaust air path means, said fresh air path means and saidexhaust air path means being disposed and configured such that during aventilation cycle, exhaust air entering the exhaust air intake sideflows through said third air stream path and then through said fourthair stream path and fresh air entering said the fresh air intake sideflows through said first air stream path and then through said secondair stream path, said ventilation apparatus including a rotationcomponent for inducing rotation of said exchanger wheel through saidfresh air path means and said exhaust air path means, defrost air pathmeans for conveying defrost air to said fresh air intake side, saiddefrost air path means being configured to connect the exhaust airdischarge side with the fresh air intake side for conveying defrost airto said fresh air intake side from said exhaust air discharge side, adamper component, said damper component being displaceable between aventilation configuration for a ventilation cycle wherein said defrostair path means is closed off and said fresh air intake side and exhaustair discharge side are open, and a defrost configuration for a defrostcycle wherein said fresh air intake side and said exhaust air dischargeside are closed off, and said defrost air path means is open, andwherein during a ventilation cycle, when said damper component is insaid ventilation configuration, fresh air is able to flow through saidfresh air path means and exhaust air is able to flow through saidexhaust air path means, and during a defrost cycle, when said dampercomponent is in said defrost configuration, defrost air taken from thebuilding, is able to circulate, for delivery back into the building,through said exhaust air intake side, through said third air streampath, through said fourth air stream path, then through said defrost airpath means, through said first air stream path, through said second airstream path and through said fresh air discharge side.
 41. A ventilationapparatus as defined in claim 40 including a defrost rotation componentfor inducing, during a defrost cycle, said rotary exchanger wheel torotate at a rotational speed of from 0 to 2 rpm.
 42. A ventilationapparatus as defined in claim 40 including a component for stopping,during a defrost cycle, said rotary exchanger wheel from rotating.
 43. Aventilation apparatus as defined in claim 42 wherein said rotationcomponent comprises an electric motor and said component for stoppingthe rotation of said exchanger wheel comprises an electric switchconfigured so as to be able to de-energize said motor during a defrostcycle.
 44. A ventilation apparatus as defined in claim 40 wherein saidsensible heat exchanger element comprises air-to-air beat exchangingwalls between said first and fourth air paths.
 45. A ventilationapparatus as defined in claim 44 wherein said sensible heat exchangerelement is of a rectangular parallelepiped shape, the first and fourthair paths thereof are disposed at right angles to each other and saidsensible heat exchanger element is so disposed such that the first andfourth air paths are diagonally oriented so that they are self draining.46. A ventilation apparatus as defined in claim 40 wherein said sensibleheat exchanger element is a rotary sensible heat exchanger wheelconfigured and rotatably disposed so as to define said first and fourthair stream paths and said apparatus includes a rotation component forinducing rotation of said sensible heat exchanger wheel through saidfresh air path means and said exhaust air path means.
 47. A ventilationapparatus as defined in claim 40 wherein said fresh air path meansincludes a fan for moving fresh air through said fresh air path meansand said exhaust air means includes a fan for moving exhaust air throughsaid exhaust air path means.
 48. A ventilation apparatus as defined inclaim 40 wherein said damper means comprises a first damper componentand a second damper component, said first damper component beingdisplaceable between a ventilation configuration wherein said defrostair path means is closed off and said fresh air intake side is open anda defrost configuration wherein said defrost air path means is open andsaid fresh air intake side is closed off and said second dampercomponent being displaceable between a ventilation configuration whereinsaid exhaust air discharge side is open and a defrost configurationwherein said exhaust air discharge side is closed off, and whereinduring a ventilation cycle, when said first and second damper componentsare in said respective ventilation configurations, fresh air is able toflow through said fresh air path means and exhaust is able to flowthrough said exhaust air path means, and during a defrost cycle, whensaid first and second damper components are in said respective defrostconfigurations, defrost air taken from the building, is able tocirculate, for delivery back into the building, through said exhaust airintake side, through said second air stream path, then through saiddefrost air path means, through said first air stream path, and throughsaid fresh air discharge side.
 49. The ventilation apparatus as definedin claim 48 wherein said fresh air path means, said exhaust air pathmeans, said rotary exchanger wheel, and said defrost air path means, aredisposed in a cabinet, wherein said fresh air intake side, said exhaustair discharge side, said fresh air discharge side and said exhaust airintake side each includes one respective air opening in an outer wall ofsaid cabinet, wherein a partition wall in said cabinet separates saidexhaust air discharge side with said fresh air intake side, and whereinsaid defrost air path means comprises an opening in said partition wall.50. A ventilation apparatus as defined in claim 49 wherein saidapparatus includes fan means mounted in said cabinet for moving freshair through said fresh air path means and for moving exhaust air throughsaid exhaust air path means, said fan means comprising one motor and twoblower wheels operatively connected thereto, said fresh air path meansincluding one said blower wheel and said exhaust path means includingthe other said blower wheel.
 51. A defrostable ventilation apparatus,for exchanging air between the interior and exterior of a building, fortransferring water moisture and sensible heat between exhaust air takenfrom the building and fresh air taken from the exterior ambient air fordelivery to the building, and wherein air from the interior of thebuilding is used as defrost air to defrost the ventilation apparatus,said ventilation apparatus comprising fresh air path means having afresh air intake side and a fresh air discharge side, exhaust air pathmeans having an exhaust air intake side and an exhaust air dischargeside, an exchanger comprising a desiccant exchanger element for transferof water moisture and sensible heat between said exhaust air and saidfresh air, and a sensible heat exchanger element for transfer ofsensible heat between said exhaust air and said fresh air, saiddesiccant exchanger element comprising a rotary exchanger wheelconfigured and rotatably disposed so as to define a second air streampath and a third air stream path, said second air stream path defining aportion of said fresh air path means and said third air stream pathdefining a portion of said exhaust air path means, said sensible heatexchanger element comprising a first air path defining a portion of saidfresh air path means and a fourth air path defining a portion of saidexhaust air path means, said first and second air stream paths definingrespective portions of said fresh air path means between the intake anddischarge sides of said fresh air path means, said third and fourth airstream paths defining respective portions of said exhaust air path meansbetween the intake and discharge sides of said exhaust air path means,said fresh air path means and said exhaust air path means being disposedand configured such that during a ventilation cycle, exhaust airentering the exhaust air intake side flows through said third air streampath and then through said fourth air stream path and fresh enteringsaid the fresh air intake side flows through said first air stream pathand then through said second air stream path, said ventilation apparatusincluding a rotation component for inducing rotation of said exchangerwheel through said fresh air path means and said exhaust air path means,defrost air path means for providing an air path by-passing said firstair steam path, said defrost air path means comprising a defrost airdischarge side and being configured to connect the exhaust air dischargeside with the defrost air discharge side thereof for conveying defrostair to said defrost air discharge side from said exhaust air dischargeside, and a damper component, said damper component being displaceablebetween a ventilation configuration for a ventilation cycle wherein saiddefrost air path means is closed off and said fresh air intake side andsaid exhaust air discharge side are open, and a defrost configurationfor a defrost cycle wherein said fresh air intake side and said exhaustair discharge side are closed off and said defrost air path means isopen, and wherein during a ventilation cycle, when said damper componentis in said ventilation configuration, fresh air is able to flow throughsaid fresh air path means and exhaust air is able to flow through saidexhaust air path means, and during a defrost cycle, when said dampercomponent is in said defrost configuration, defrost air taken from thebuilding, is able to circulate, for delivery back into the building,through said exhaust air intake side, through said second air streampath, then through said defrost air path means, and through said defrostair discharge side.
 52. A defrostable ventilation apparatus, forexchanging air between the interior and exterior of a building, fortransferring water moisture and sensible heat between exhaust air takenfrom the building and fresh air taken from the exterior ambient air fordelivery to the building, and wherein air from the interior of thebuilding is used as defrost air to defrost the ventilation apparatus,said ventilation apparatus comprising fresh air path means having afresh air intake side and a fresh air discharge side, exhaust air pathmeans having an exhaust air intake side and an exhaust air dischargeside, an exchanger comprising a desiccant exchanger element for transferof water moisture and sensible heat between said exhaust air and saidfresh air, and a sensible heat exchanger element for transfer ofsensible heat between said exhaust air and said fresh air, saiddesiccant exchanger element comprising a rotary exchanger wheelconfigured and rotatably disposed so as to define a second air streampath and a third air stream path, said second air stream path defining aportion of said fresh air path means and said third air stream pathdefining a portion of said exhaust air path means, said sensible heatexchanger element comprising a first air path defining a portion of saidfresh air path means and a fourth air path defining a portion of saidexhaust air path means, said first and second air stream paths definingrespective portions of said fresh air path means between the intake anddischarge sides of said fresh air path means, said third and fourth airstream paths defining respective portions of said exhaust air path meansbetween the intake and discharge sides of said exhaust air path means,said fresh air path means and said exhaust air path means being disposedand configured such that during a ventilation cycle, exhaust airentering the exhaust air intake side flows through said third air streampath and then through said fourth air stream path and fresh enteringsaid the fresh air intake side flows through said first air stream pathand then through said second air stream path, said ventilation apparatusincluding a rotation component for inducing rotation of said exchangerwheel through said fresh air path means and said exhaust air path means,defrost air path means for providing an air path by-passing said firstair steam path, said defrost air path means being configured to connectthe exhaust air discharge side with the fresh air discharge side forconveying defrost air to said fresh air discharge side from said exhaustair discharge side, and a damper component, said damper component beingdisplaceable between a ventilation configuration for a ventilation cyclewherein said defrost air path means is closed off and said fresh airintake side and exhaust air discharge side are open, and a defrostconfiguration for a defrost cycle wherein said fresh air intake side andsaid exhaust air discharge side are closed off, and said defrost airpath means is open, and wherein during a ventilation cycle, when saiddamper component is in said ventilation configuration, fresh air is ableto flow through said fresh air path means and exhaust air is able toflow through said exhaust air path means, and during a defrost cycle,when said damper component is in said defrost configuration, defrost airtaken from the building, is able to circulate, for delivery back intothe building, through said exhaust air intake side, through said secondair stream path, then through said defrost air path means, and throughsaid fresh air discharge side.